The Mössbauer Effect(ME) is frequently used to investigate magnetically ordered systems. One usually assumes that the magnetic order induces a hyperfine magnetic field, $B_{hyperfine}$, at the ME active site. This is the case in the ruthenates, where the temperature dependence of $B_{hyperfine}$ at $^{99}$Ru sites tracks the temperature dependence of the ferromagnetic or antiferromagnetic order. However this does not happen in the rare-earth intermetallics, GdRu$_2$ and HoRu$_2$. Specific heat, magnetization, magnetic susceptibility, Mössbauer effect, and neutron diffraction have been used to study the nature of the magnetic order in these materials. Both materials are found to order ferromagnetically at 82.3 and 15.3 K, respectively. Despite the ferromagnetic order of the rare earth moments in both systems, there is no evidence of a correspondingly large $B_{hyperfine}$ in the Mössbauer spectrum at the Ru site. Instead the measured spectra consist of a narrow peak at all temperatures which points to the absence of magnetic order. To understand the surprising absence of a transferred hyperfine magnetic field, we carried out {\it ab initio} calculations which show that spin polarization is present only on the rare-earth site. The electron spin at the Ru sites is effectively unpolarized and, as a result, $B_{hyperfine}$ is very small at those sites. This occurs because the 4$d$ Ru electrons form broad conduction bands rather than localized moments. These 4$d$ conduction bands are polarized in the region of the Fermi energy and mediate the interaction between the localized rare earth moments.
We report the existence of a field-induced ferromagnetic transition in the magnetically ordered state (<69 K) of an intermetallic compound, Tb5Si3, and this transition is distinctly first-order at 1.8 K (near 60 kOe), whereas it appears to become second order near 20 K. The finding we stress is that the electrical resistivity becomes suddenly large in the high-field state after this transition and this is observed in the entire temperature range in the magnetically ordered state. Such an enhancement of 'positive' magnetoresistance (below 100 kOe) at the metamagnetic transition field is unexpec…
Based on magnetization, specific heat, magnetostriction, and neutron diffraction studies on single-crystal TbCo2B2C, it is found out that the paramagnetic properties, down to liquid nitrogen temperatures, are well described by a Curie-Weiss behavior of the Tb+3 moments. Furthermore, below Tc= 6.3 K, the Tb-sublattice undergoes a ferromagnetic (FM) phase transition with the easy axis being along the (100) direction and, concomitantly, the unit cell undergoes a tetragonal-to-orthorhhombic distortion. For fields up to 90 kOe, no field-induced splitting of the Co 3d orbitals was observed; as such …
The compound, Nd7Rh3, crystallizing in Th7Fe3-type hexagonal structure, was previously known to exhibit two magnetic transitions, one at 32 K and the other at 10 K (in zero magnetic field). Here, we report the existence of a field-induced first-order antiferromagnetic to ferromagnetic transition at 1.8 K in this compound. On the basis of the measurements of isothermal magnetization and magnetoresistance, we provide evidence for the occurence of kinetic-hindrance, proposed in the literature, resulting in phase co-existence (super-cooled ferromagnetic + antifferomagnetic) and percolative electri…
Field-induced magnetization jumps with similar characteristics are observed at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even the existence- of these jumps depends critically on the magnetic field sweep rate used to record the data. It is proposed that, for both compounds, the martensitic character of their antiferromagnetic-to-ferromagnetic transitions is at the origin of the magnetization steps.
Exchange bias effect is an important attribute in several device applications. Traditionally, it is discussed as a form of exchange anisotropy at the interface between the ferromagnetic/antiferromagnetic layers of two distinct systems. We report here on the magnetically ordered alloys possessing the feature of unidirectional anisotropy, which reverses its sign across a characteristic temperature. These are admixed rare earth intermetallics, comprising two dissimilar rare earth (RE) ions, belonging to the two different halves of the 4f-series and imbibing the notion of ferromagnetic coupling be…
We have investigated the ferromagnetic phase transition of elemental Co by high-resolution neutron backscattering spectroscopy. We monitored the splitting of the nuclear levels by the hyperfine field at the Co nucleus. The energy of this hyperfine splitting is identified as the order parameter of the ferromagnetic phase transition. By measuring the temperature dependence of the energy we determined the critical exponent $β= 0.350 \pm 0.002$ and the ferromagnetic Curie temperature of $T_{\text{C}} = 1400$~K. The present result of the critical exponent agrees better with the predicted value (0.3…
Magnetic phases for the intermetallic compound NdMn1.4Co0.6Si2 have been investigated at various temperatures by dc magnetization, neutron diffraction and neutron depolarization. Our study shows multiple magnetic phase transitions with temperature (T) over 1.5-300 K. In agreement with dc-magnetization and neutron depolarization results, the temperature dependence of the neutron diffraction patterns shows five distinct regions with different magnetic phases. These temperature regions are (i) T >= 215 K, (ii) 215 K > T >= 50 K, (iii) 50 K > T >= 40 K, (iv) 40 K > T > 15 K, and (v) T =< 15 K. The…
We report the magnetic properties strongly varying with the rare-earth elements in the newly found ternary compounds $R$Al$_{0.9}$Si$_{1.1}$, which crystallize in the tetragonal $α$-ThSi$_2$-type structure. For $R$ = Ce the alloy has a weak ferromagnetism below 11 K and for $R$ = Pr it orders ferromagnetically at 17 K, while for $R$ = Gd it is antiferromagnetic with $T_{\rm N}$ = 30.5 K. In addition, we find no field effect on $T_{\rm N}$ of $R$ = Gd because of the large internal mean field, but significant changes in the magnetic properties of $R$ = Ce and Pr.
We study the formation of local magnetic moments and magnetic hyperfine fields at an \textit{s-p} impurity diluted in intermetallic Laves phases compounds $R$Ni$_{2}$ ($R$ = Nd, Sm, Gd, Tb, Dy) at finite temperatures. We start with a clean host and later the impurity is introduced. The host has two-coupled ($R$ and Ni) sublattice Hubbard Hamiltonians but the Ni sublattice can be disregarded because its $\textit{d}$ band, being full, is magnetically ineffective. Also, the effect of the $\textit{4f}$ electrons of $R$ is represented by a polarization of the \textit{d} band that would be produced …
Novel thermal effects across the first order antiferromagnetic (AFM) - ferromagnetic (FM) transition in an intermetallic alloy are reported. They show instances of warming when heat is extracted from the sample, and cooling when heat is provided to the sample across AFM-FM transition in Ta doped $HfFe_2$, thus providing indisputable evidence of metastable supercooled AFM and superheated FM states, respectively. Such thermal effects in a magnetic solid prepared from commercially available materials has been reported for the first time. The transition proceeds in multiple steps which is interpre…
Recent experimental results for the magnetic hyperfine field B_{\rm hf} at the nuclei of \textit{s-p} impurities such as ${}^{119}$Sn in intermetallic Laves phases RM_2 (R = Gd, Tb, Dy, Ho, Er; M = Fe, Co) and ${}^{111}$Cd in RCo_{2}, the impurity occupying a $R$ site indicate that the ratio B_{\rm hf}/μ_{3d} exhibits different behavior when one goes from RFe_2 to RCo_2. In this work, we calculate these local moments and the magnetic hyperfine fields. In our model, B_{\rm hf} has two contributions: one arising from the $R$ ions, and the other arising from magnetic 3d-elements; these separate c…
Using Mössbauer and EPR spectroscopy we have studied the insulating ferromagnetic La$_{1-x}$Ca$_x$Mn$_{0.99}$$^{57}$Fe$_{0.01}$O$_3$ ($x=0.175$) compound prepared in air and reduced atmosphere. The average hyperfine field follows a mean field approximation solution in contrast with the ferromagnetic metallic regime where it significantly deviates from the order parameter deduced from neutron diffraction data or mean field approximation. Although the magnetic measurements show remarkable differences between air prepared and reduced R samples the corresponding Mössbauer spectra are almost identi…
C14 Nb(Fe89.4Al10.6)2 Laves phase intermetallic compound was investigated by DC magnetization (M) measurements performed in the temperature (T) interval of 20 to 175 K,under an applied magnetic field (H) ranging between 50 and 1250 Oe. Magnetization curves were recorded in the field-cooled (FC) and in the zero-field-cooled (ZFC) modes. They clearly showed an irreversible character that vanished at H=1250 Oe. Both magnetization curves exhibited well-defined peaks around T_N =72.3 K whose positions were H-independent, so they were identified as the compound's Néel temperature. The existence of i…
In this paper, we have found a family of intermetallic compounds YMn12-xFex (x = 6.6-8.8) showing a bulk form of tunable giant exchange bias effect which arises from global interactions among ferromagnetic (FM) and antiferromagnetic (AFM) sublattices but not the interfacial exchange coupling or inhomogeneous magnetic clusters. A giant exchange bias with a loop shift up to 6.1 kOe has been observed in YMn4.4Fe7.6 compound with the strongest competing magnetic interactions. In a narrow temperature range, the exchange bias field shows a sudden switching off whereas the coercivity shows a sudden s…
Systematic experimental (vibrating sample magnetometry) and theoretical (electronic structure calculations using charge and spin self-consistent Korringa-Kohn-Rostoker Green function method) studies were performed on a series of intermetallic sigma-phase Fe(100-x)Re(x) (x = 43-53) compounds. Clear evidence was found that all investigated samples exhibit magnetism with an ordering temperature ranging between 65 K for x = 43 and 23 K for x = 53. The magnetism was revealed to be itinerant and identified as a spin-glass (SG) possibly having a re-entrant character. The SG was found to be heterogene…
Magnetic and heat capacity measurements have been carried out on the polycrystalline sample of DyNi which crystallizes in the orthorhombic FeB structure (space group Pnma). This compound is ferromagnetic with a Curie temperature of 59 K. Magnetization-field isotherms at low temperatures shows a step-like behavior characteristic of metamagnetic transitions. The magnetocaloric effect has been measured both in terms of isothermal magnetic entropy change and adiabatic temperature change for various applied magnetic fields. The maximum values of the entropy change and the temperature change are fou…
We report on the synthesis and physical properties of the new ternary intermetallic Ce$_2$Rh$_2$Ga. Its formation and dimorphism have been investigated by powder and single crystal X-ray diffractometry, as well as by differential thermal analyses. LT- and HT-Ce$_2$Rh$_2$Ga can be obtained by the chosen respective thermal treatment. The high-temperature form (HT-Ce$_2$Rh$_2$Ga), stable above 864(5)°C, is orthorhombic La2Ni3-type [Cmce, oS20, a=5.851(2) Å, b=9.618 (2) Å, c=7.487 (2) Å, V=421.3(2) Å3]; the low-temperature form (LT-Ce$_2$Rh$_2$Ga), stable below this temperature, is monoclinic Pr2C…
We report on the physical properties of single crystalline EuRhSi$_3$ and polycrystalline EuIrSi$_3$, inferred from magnetisation, electrical transport, heat capacity and $^{151}$Eu Mössbauer spectroscopy. These previously known compounds crystallise in the tetragonal BaNiSn$_3$-type structure. The single crystal magnetisation in EuRhSi$_3$ has a strongly anisotropic behaviour at 2 K with a spin-flop field of 13 T, and we present a model of these magnetic properties which allows the exchange constants to be determined. In both compounds, specific heat shows the presence of a cascade of two clo…
UCoGa and URhGa, two isostructural compounds show opposite signs of the initial response of Curie temperature to applied hydrostatic premenssure. To determine the physical origin of this contradiction the magnetization data measured with respect to temperature, magnetic field and hydrostatic pressure were analyzed in the framework of the Takahashi's spin-fluctuation theory. The parameters T0 and TA characterizing the distribution widths of the spin-fluctuation spectrum in the energy and wave vector space, respectively, and TC/T0, the degree of the 5f-electron localization have been determined.…
Magnetization (M) and magnetoresistance (MR) measurements on polycrystalline R2Mn3Si5 (R = Tb, Dy and Ho) compounds (tetragonal, space group P4/mnc) have been carried out in the temperature range of 2 K-300 K, in various applied fields. Both, the rare earth and the Mn, are found to carry magnetic moments in these compounds. Mn has two sub-lattices (Mn1 and Mn2) that order magnetically at two different temperatures. Rare earth and Mn1 moments order ferromagnetically at TC1 whereas Mn2 is found to magnetically order at TC2 (TC1 = 89 K, 86 K, 78 K and TC2 = 18 K, 34 K, 16 K for R = Tb, Dy and Ho …
The Ce(1-x)LaxCrGe3 (x = 0, 0.19, 0.43, 0.58 and 1) intermetallic compound system has been investigated by magnetization measurements and neutron scattering techniques to determine the effect of La-doping on the magnetic ordering and exchange interaction between Cr ions. The structural and magnetic characterization in this series was first verified by X-ray diffraction and bulk magnetization measurements. The samples exhibit the known hexagonal perovskite structure (P63/mmc space group) and have a single magnetic phase according to magnetization measurements. In this work, the ferromagnetic or…
Thermal expansion, magnetostriction and magnetization measurements under magnetic field and hydrostatic pressure were performed on a $\mathrm{UAu_{2}Si_{2}}$ single crystal. They revealed a large anisotropy of magnetoelastic properties manifested by prominent length changes leading to a collapse of the unit-cell volume accompanied by breaking the fourfold symmetry (similar to that in $\mathrm{URu_{2}Si_{2}}$ in the hidden-order state) in the antiferromagnetic state as consequences of strong magnetoelastic coupling. The magnetostriction curves measured at higher temperatures confirm a bulk char…
In this work we investigate Ising and classical Heisenberg models for two and three dimensional lattices in presence of diluted ferromagnetic dimers. For such models the Curie temperature as a function of ratio of intra-dimer exchange coupling constant I_A and other inter-site coupling constants I_B is calculated. In case dimer is treated exactly and environment within the mean-field approach it was found that even for I_A/I_B\to\infty T_C remains finite. Similar analysis is proposed for rhombohedral phase of intermetallic compound Gd2Fe17 where so-called Fe1-Fe1 "dumbbell" forms the diluted f…
The quantum critical point (QCP) in the archetypical heavy-fermion compound CeCu$_6$ doped by Au is described, accounting for the localized $4f$-electron of Ce, using realistic electronic structure calculations combined with dynamical mean-field theory (DMFT). Magnetism trends in Ce(Cu$_{1-ε}$Au$_ε$)$_6$ are compared with those in Co-doped CeCu$_{5}$, which resides on the non-ferromagnetic side of the composition space of one of the earliest rare-earth permanent magnet compounds, Ce(Co,Cu)$_5$. The construction of a realistic Doniach phase diagram shows that the system crosses over a magnetic …
At low temperatures, the intermetallic compound Gd$_5$Ge$_4$ shows a sharp field-induced transition into a ferromagnetic state around 25 kOe of applied field. The material remains in the field treated ferromagnetic state even when the magnetic field is removed. We have investigated the character of this field-treated state by magnetization and heat capacity measurements. The nature of the magnetization and the heat capacity are found to be different above and below a charactersitic temperature Tirr = 25 K.
Electrons in a two-dimensional semiconducting heterostructure interact with nuclear spins via the hyperfine interaction. Using a a Kondo lattice formulation of the electron-nuclear spin interaction, we show that the nuclear spin system within an interacting two-dimensional electron gas undergoes a ferromagnetic phase transition at finite temperatures. We find that electron-electron interactions and non-Fermi liquid behavior substantially enhance the nuclear spin Curie temperature into the $mK$ range with decreasing electron density.
Electronic structure Korringa-Kohn-Rostoker calculations for the $σ$-phase in Fe$_{100-x}$V$_x$ were performed in compositional range of its occurance ($\sim 34 \le x \le \sim 65$). Fe and V magnetic moments and hyperfine fields were determined for five inequivalent lattice sites in two models of magnetic structure, namely ferromagnetic FM and so-called anti-parallel one, APM, dominated by antiferromagnetic coupling. The average magnetic moments calculated for FM state overestimate the experimental data, whereas the corresponding quantities computed for APM state, underestimate them. Such a be…
Complex magneto structural behaviour of rare rich intermetallic Tb$_3$Co is reported in this study. Below the 84K (T$_N$), it undergoes a first order magnetic transition 72K confirmed from specific heat and magnetization measurements. Detailed study using magnetization, specific heat, neuron diffraction and ac-susceptibility measurements suggests that the compound in the question possesses canted magnetic structure. Neutron diffraction reveals that Tb moments are aligned antiferromagnetically (AFM) in ab plane and ferromagnetically (FM) along c direction. This study focusses on the temperature…
We present a study of Cu-substitution effects in 4f-Ce intermetallic compound CeAu1-xCuxGe, with potentially unusual electronic states, in the whole concentration range (x = 0.0 - 1.0). The parent CeAuGe compound, crystallizing in a non-centrosymmetric hexagonal structure, is a ferromagnetic semimetal with Curie temperature 10 K. Cu-doping on Au-site of CeAuGe, CeAu1-xCuxGe, changes the crystal structure from the non-centrosymmetric (P63mc) to centrosymmetric (P63/mmc) space group at the concentration x ~ 0.5, where the c-lattice constant has a maximum value. Magnetic susceptibility and electr…
The magnetic properties and magnetocaloric effect of an intermetallic compound $\mathrm{Er_2Rh_3Si}$ was investigated by performing temperature dependence of dc- and ac-magnetic susceptibility and isothermal magnetizations. Polycrystalline $\mathrm{Er_2Rh_3Si}$ compound with $\mathrm{Mg_2Ni_3Si}$-type of rhombohedral Laves phases (space group $R\overline{3}m$, hR18) structure was synthesized by arc-melting method. The ac- and dc-magnetic susceptibility results revealed that the compound exhibited ferromagnetic order with $T_C$ $\approx$ 18 K. The obtained isothermal magnetic entropy changes ($…
Precise thermal expansion and magnetostriction studies of the intermetallic compound Eu$_2$CuSi$_3$ in the temperature range between 5 and 300 K are presented. A clear sign of magnetic second order phase transition at the ferromagnetic Curie temperature $T_{\rm C}$ = 34 K indicates strong magneto-structural coupling. Uniaxial thermal expansion data show a large anisotropy between the magnetic easy $c$-axis and the hexagonal $ab$-plane, which is associated with a strongly anisotropic magnetic coupling. A spin-reorientation regime as well as a non-uniform energy scale are indicated by Grüneisen …
Magnetic exchange in Kondo lattice systems is of the Ruderman-Kittel-Kasuya-Yosida type, whose sign depends on the Fermi wave vector, $k_F$ . In the simplest setting, for small $k_F$ , the interaction is predominately ferromagnetic, whereas it turns more antiferromagnetic with growing $k_F$. It is remarkable that even though $k_F$ varies vastly among the rare-earth systems, an overwhelming majority of lanthanide magnets are in fact antiferromagnets. To address this puzzle, we investigate the effects of a p-wave form factor for the Kondo coupling pertinent to nearly all rare-earth intermetallic…
While the stoichiometric intermetallic compound FeAl is found to be paramagnetic in experiment, standard band-theory approaches predict the material to be ferromagnetic. We show that this discrepancy can be overcome by a better treatment of electronic correlations with density functional plus dynamical mean field theory. Our results show no ferromagnetism down to 100 K and since the susceptibility is decreasing at the lowest temperatures studied we also do not expect ferromagnetism at even lower temperatures. This behavior is found to originate from temporal quantum fluctuations that screen sh…
We report the experimental study on the structural and magnetic properties of a new ternary intermetallic compound $\mathrm{Sm_2AgSi_3}$. The properties of the sample were investigated in detail by X-ray diffraction, dc-magnetization, and heat capacity measurements. The polycrystalline compound of $\mathrm{Sm_2AgSi_3}$ crystallizes in the $\mathrm{ThSi_2}$-type tetragonal structure (space group ${I_{4_1}/amd}$). The temperature-dependent dc-magnetization and heat capacity results demonstrate that the compound undergoes ferromagnetic behaviour with a Curie temperature ($T_C$) of 14 K. The large…
Dynamic magnetic susceptibility, $χ$, was studied in several intermetallic materials exhibiting ferromagnetic, antiferromagnetic and metamagnetic transitions. Precise measurements by using a 14 MHz tunnel diode oscillator (TDO) allow detailed insight into the field and temperature dependence of $χ$. In particular, local moment ferromagnets show a sharp peak in $χ(T)$ near the Curie temperature, $T_c$. The peak amplitude decreases and shifts to higher temperatures with very small applied dc fields. Anisotropic measurements of CeVSb$_3$ show that this peak is present provided the magnetic easy a…
$^{73}$Ge and $^{59}$Co nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements have been performed on a $^{73}$Ge-enriched single-crystalline sample of the ferromagnetic superconductor UCoGe in the paramagnetic state. The $^{73}$Ge NQR parameters deduced from NQR and NMR are close to those of another isostructural ferromagnetic superconductor URhGe. The Knight shifts of the Ge and Co sites are well scaled to each other when the magnetic field is parallel to the $b$ or $c$ axis. The hyperfine coupling constants of Ge are estimated to be close to those of Co. The la…
The different magnetic phases of the intermetallic compound Nd$_5$Ge$_3$ are studied in terms of the specific heat, in a broad range of temperatures (350~mK--140~K) and magnetic fields (up to 40 kOe). The expected $T^{3}$ and $T^{3/2}$ terms are not found in the antiferromagnetic (AFM) and ferromagnetic (FM) phases respectively, but a gapped $T^2$ contribution that originates from a mixture of AFM and FM interactions in different dimensionalities under a large magnetocrystalline anisotropy, is present in both. An almost identical Schottky anomaly, that arises from the hyperfine splitting of th…
We report the effect of Ga substitution on magnetization, magnetoresistance, and magnetostriction in polycrystalline Pr0.6Sr0.4Co1-yGayO3 (y=0.0-0.3) samples. Upon substitution of the non-magnetic Ga3+ cation for magnetic Co3+, the low-temperature ground state transforms from ferromagnetic metallic for y = 0 to cluster glass semiconductor for y = 0.2. Magnetoresistance at 7T is negative and its magnitude increases from 2 percentage for y = 0 to 30 percentage for y = 0.3 at 10 K. On the other hand, magnetostriction at 10 K is positive and its value decreases with increasing y. Interestingly, th…
In this study we report the results of study of novel ternary $Np_2PtGa_3$ compound. The x-ray-powder diffraction analysis reveals that the compound crystallizes in the orthorhombic CeCu$_2$-type crystal structure (space group Imma) with lattice parameters $a$ = 0.4409(2) nm, $b$ = 0.7077(3) nm and $c$ = 0.7683(3) nm at room temperature. The measurements of dc magnetization, specific heat and electron transport properties in the temperature range 1.7 - 300 K and in magnetic fields up to 9 T imply that this intermetallic compound belongs to a class of ferromagnetic Kondo systems. The Curie temp…
FeGa$_3$ is an unusual intermetallic semiconductor that presents intriguing magnetic responses to the tuning of its electronic properties. When doped with Ge, the system evolves from diamagnetic to paramagnetic to ferromagnetic ground states that are not well understood. In this work, we have performed a joint theoretical and experimental study of FeGa$_{3-x}$Ge$_x$ using Density Functional Theory and magnetic susceptibility measurements. For low Ge concentrations we observe the formation of localized moments on some Fe atoms and, as the dopant concentration increases, a more delocalized magne…
We report temperature and field dependent measurements of the magnetic susceptibility, specific heat and resistivity of sintered YbB2 pellets, prepared via two distinct reaction routes, utilizing different temperatures, pressures and sintering times. Sample behavior is affected by the preparation procedure, as a consequence of different secondary phases, most of which were identified via x-ray diffraction. These experiments show that YbB2 is a metal with the Yb atoms in or very close to their 3+ state. YbB2 appears to order anti-ferromagnetically at TN ~ 5.6 K, which can be considered a relati…
The intermetallic compound SmMn$_2$Ge$_2$, displaying multiple magnetic phase transitions, is being investigated in detail for its magnetization behavior near the 145 K first order ferromagnetic to antiferromagnetic transition occuring on cooling, in particular for thermomagnetic history effects in the magnetization data. The most unusual finding is that the thermomagnetic irreversibility, [= M$^{FCW}$(T)-M$^{ZFC}$(T)] at 135 K is higher in intermediate magnetic field strengths. By studying the response of the sample (i.e., thermomagnetic irreversibility and thermal hysteresis) to different hi…
We report a polarized neutron diffraction study conducted to reveal the nature of the weak ferromagnetic moment in the superconducting ferromagnet UCoGe. We find that the ordered moment in the normal phase in low magnetic fields (B // c) is predominantly located at the U atom and has a magnitude of about 0.1 muB at 3 T, in agreement with bulk magnetization data. By increasing the magnetic field the U moment grows to about 0.3 muB in 12 T and most remarkably, induces a substantial moment (about 0.2 muB) on the Co atom directed antiparallel to the U moment. The anomalous polarizability of the Co…
We report the synthesis, structure, and magnetic and transport properties of a new ternary intermetallic compound PrRhSn3 which crystallizes in LaRuSn3-type cubic structure (space group Pm-3n). At low applied fields the dc magnetic susceptibility exhibits a sharp anomaly below 6~K with an irreversible behavior in zero field cooled (ZFC) and field cooled (FC) susceptibility below 5.5 K. The ac susceptibility exhibits a frequency dependent anomaly revealing a spin-glass behavior with a freezing temperature, T_f = 4.3 K. The observation of spin-glass behavior is further supported by a very slow d…
The rare-earth based ternary intermetallic compounds $R_2TX_3$ ($R$ = rare-earth, $T$ = transition-metal, $X$ = Si, Ge, Ga, In) have attracted considerable interest due to a wide range of interesting low temperature properties. Here we investigate the magnetic state of Nd$_{2}$PdSi$_{3}$ using neutron diffraction, muon spin relaxation ($μ$SR) and inelastic neutron scattering (INS). This compound appears anomalous among the $R_{2}$PdSi$_{3}$ series, since it was proposed to order ferromagnetically, whereas others in this series are antiferromagnets. Although some members of the $R_2TX_3$ series…
The Mn spin correlations were studied near the O'-O phase transition at T{JT} = 750 K, up to 950 K with 17O and 139La NMR in a stoichiometric LaMnO3 crystalline sample. The measured local hyperfine fields originate from the electron density transfered from the eg- and t2g-orbitals to the 2s(O) and 6s(La) orbits, respectively. By probing the oxygen nuclei, we show that the correlations of the Mn spins are ferromagnetic in the ab-plane and robust up to T{JT} whereas along the c-axis, they are antiferromagnetic and start to melt below T{JT}, at about 550 K. Above T{JT} the ferromagnetic Mn-Mn exc…
We have synthesized single crystals of CeZnAl$_3$, which is a new member of the family of the Ce-based intermetallics Ce$TX_3$ ($T$ = transition metal, $X$= Si, Ge, Al), crystallizing in the non-centrosymmetric tetragonal BaNiSn$_3$-type structure. Magnetization, specific heat and resistivity measurements all show that CeZnAl$_3$ orders magnetically below around 4.4 K. Furthermore, magnetization measurements exhibit a hysteresis loop at low temperatures and fields, indicating the presence of a ferromagnetic component in the magnetic state. This points to a different nature of the magnetism in …
Among the members of the series R2PdSi3 (R= Rare-earths), the magnetic behavior of the Nd compound is interesting in some respects. This compound is considered to order ferromagnetically (below 16 K), unlike other members of this series which order antiferromagnetically. In addition, magnetic ordering temperature (To) is significantly enhanced with respect to de Gennes scaled value. In order to understand the magnetism of this compound better, we have investigated the magnetic behavior in detail (under external pressure as well) and also of its solid solutions based on substitutions at Nd and …
We present detailed investigations in single crystals of two recently reported quaternary intermetallic compounds EuRhAl$_4$Si$_2$ and EuIrAl$_4$Si$_2$ employing magnetization, electrical resistivity in zero and applied fields, heat capacity and $^{151}$Eu Mössbauer spectroscopy measurements. The two compounds order antiferromagnetically at $T_{\rm N1}$ = 11.7 and 14.7\,K, respectively, each undergoing two magnetic transitions: the first from paramagnetic to incommensurate modulated antiferromagnetic, the second at lower temperature to a commensurate antiferromagnetic phase as confirmed by hea…
A new quaternary intermetallic borocarbide TmCo2B2C has been synthesized via a rapid-quench of an arc-melted ingot. Elemental and powder-diffraction analyses established its correct stoichiometry and single-phase character. The crystal structure is isomorphous to that of TmNi2B2C(I4/mmm) and is stable over the studied temperature range. Above 7 K, the paramagnetic state follows the modified Curie-Weiss behavior (X=C/(T-theta)+X0 wherein X0=0.008(1) emu/mole and the temperature-dependent term reflecting the paramagnetism of the Tm subsystem: ueff=7.6(2) uB [in agreement with the expected value …
We report on a solution-growth based method to synthesise single crystals of Y$_2$Co$_3$ and on its structural and magnetic properties. We find that Y$_2$Co$_3$ crystallizes in the La2Ni3-type orthorhombic structure with space group Cmce (No. 64), with Co forming distorted kagome lattices. Y$_2$Co$_3$ orders antiferromagnetically below $T_N$ = 252 K. Magnetization measurements reveal that the moments are primarily aligned along the b axis with evidence for some canting. Band-structure calculations indicate that ferromagnetic and antiferromagnetic orders are nearly degenerate, at odds with expe…
Spherical nanoparticles (NPs) of size 14 nm, made of intermetallic Fe2CoAl (FCA) Heusler alloy, are synthesized via the co-precipitation and thermal deoxidization method. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns confirm that the present nanoalloy is crystallized in A2-disordered cubic Heusler structure. Magnetic field (H) and temperature (T) dependent magnetization (M) results reveal that the NPs are soft ferromagnetic (FM) with high saturation magnetization (Ms) and Curie temperature (Tc). Fe2CoAl nanoalloy does not follow the Slater Pauling (SP) rule, po…
We report on muon spin rotation (muSR) studies of the superconducting and magnetic properties of the ternary intermetallic stannide Ca3Ir4Sn13. This material has recently been the focus of intense research activity due to a proposed interplay of ferromagnetic spin fluctuations and superconductivity. In the temperature range T=1.6-200 K, we find that the zero-field muon relaxation rate is very low and does not provide evidence for spin fluctuations on the muSR time scale. The field-induced magnetization cannot be attributed to localized magnetic moments. In particular, our muSR data reveal that…
