The influence of spin and charge fluctuations on the pressure dependence of the Neel temperature near a quantum phase transition in rare-earth intermetallic compounds
In the one-loop approximation for the periodic Anderson model the contributions of spin and charge fluctuations to the renormalization of the antiferromagnetic order parameter are calculated. It is shown that taking into account the fluctuation corrections allows to quantitatively describe the pressure dependence of the Neel temperature observed in quasi-two-dimensional intermetallic antiferromagnet with heavy fermions CeRhIn$_5$.
The understanding of magnetic and electronic properties of rare-earth intermetallics is summarized. The properties of NdNi5 or ErNi5 are understood by considering a few electronic subsystems like the f electronic subsystem and the conduction-electron subsystem. The localized f electrons can give a substantial contribution to the low temperature specific heat with the entropy of R ln2 in case of Kramers ions. In this view the heavy-fermion behaviour is related with the removal of the Kramers degeneracy of the ground state of the f electronic subsystem.
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.
Neutron diffraction measurements on a high quality single crystal of CeAu2Ge2 reveal two new magnetic structures that coexist with commensurate long range antiferromagnetic order below the Neel temperature T_N ~ 14 K. The new magnetic structures, which exhibit distinct temperature and field dependencies, are described by both commensurate and incommensurate magnetic structures and introduces new region in the H-T phase diagram. These new experimental observations provide essential information for developing a universal understanding of the magnetic properties of this class of Ce-based CeX2M2 (…
The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively investigated during last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress of magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s) (Zn, Mg, and Cd). Some of them are exhibiting promising MCE properties which make them also attractive for low temperature magnetic refrigeration…
Local magnetic properties of the rare-earth intermetallics $R$Mn$_2$Ge$_2$ ($R$=Ce, Pr, Nd)
Durham University（杜伦大学）；PSI Center for Neutron and Muon Sciences（瑞士保罗谢勒研究所中子与μ子科学中心）；ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory（英国科学与技术设施委员会卢瑟福阿普尔顿实验室ISIS中子与μ子源）；University of Oxford（牛津大学）；University of Warwick（华威大学）
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…
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…
We report on the experimental evidences for an unusual coupling between the magnetic field- induced fluctuations of correlated Ce-ions coinciding with the discontinuous movement of the underlying spin density wave in the intermetallic rare earth compound CeAg2Ge2. The measurements performed using neutron scattering and magnetic Gruneisen ratio methods suggest that the coupling onsets at H= 2.7 T, T < 3.8 K and persists to the lowest measurement temperature T ~ 0.05 K. These measurements suggest a new mechanism behind the spin fluctuations which can affect the intrinsic properties of the system…
Crystal electric field states in rare earth intermetallics show an intricate entanglement with the many-body physics that occurs in these systems and that is known to lead to a plethora of electronic phases. Here, we attempt to trace different contributions to the crystal electric field (CEF) splittings in CeIrIn$_5$, a heavy-fermion compound and member of the Ce$M$In$_5$ ($M$= Co, Rh, Ir) family. To this end, we utilize high-resolution resonant angle-resolved photoemission spectroscopy (ARPES) and present a spectroscopic study of the electronic structure of this unconventional superconductor …
Cerium-based intermetallics are currently attracting much interest as a possible alternative to existing high-performance magnets containing scarce heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in these systems are poorly understood due to the difficulty of a quantitative description of the Kondo effect, a many-body phenomenon where conduction electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in Ce-Fe intermetallics is partially Kondo screened. The Kondo scale is dramatically enhanced by nitrogen interstitials completely suppressing the Ce-…
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…
We report an unusual temperature (T) dependent electrical resistivity($ρ$) behavior in a class of ternary intermetallic compounds of the type RCuAs$_2$ (R= Rare-earths). For some rare-earths (Sm, Gd, Tb and Dy) with negligible 4f-hybridization, there is a pronounced minimum in $ρ$(T) far above respective Néel temperatures (T$_N$). However, for the rare-earths which are more prone to exhibit such a $ρ$(T) minimum due to 4f-covalent mixing and the Kondo effect, this minimum is depressed. These findings, difficult to explain within the hither-to-known concepts, present an interesting scenario in …
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 …
Crystal-field (CF) effects on the rare-earth (RE) ions in ferrimagnetic intermetallics NdCo$_5$ and TbCo$_5$ are evaluated using an ab initio density functional + dynamical mean-field theory approach in conjunction with a quasi-atomic approximation for on-site electronic correlations on the localized 4$f$ shell. The study reveals an important role of the high-order sectoral harmonic component of the CF in the magnetism of RECo$_5$ intermetallics. An unexpectedly large value is computed in the both systems for the corresponding crystal-field parameter (CFP) $A_6^6 \langle r^6 \rangle$, far beyo…
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…
Most of the searches for Kitaev materials deal with $4d/5d$ magnets with spin-orbit-coupled ${J=1/2}$ local moments such as iridates and $α$-RuCl$_3$. Here we propose the monoclinic YbCl$_3$ with a Yb$^{3+}$ honeycomb lattice for the exploration of Kiteav physics. We perform thermodynamic, $ac$ susceptibility, angle-dependent magnetic torque and neutron diffraction measurements on YbCl$_3$ single crystal. We find that the Yb$^{3+}$ ion exhibits a Kramers doublet ground state that gives rise to an effective spin ${J_{\text{eff}}=1/2}$ local moment. The compound exhibits short-range magnetic ord…
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…
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 …
Heavy-fermion materials are mostly rare-earth or actinide intermetallics with very few exceptions in d-electron systems. The physical mechanism for these d-electron heavy fermion systems remains unclear. Here by studying the quadruple-perovskite CaCu3Ir4O12, we propose a symmetry-based mechanism that may enforce heavy-fermion physics in d-electron systems. We show that electron hoppings between neighboring Cu 3d-orbitals are strictly prohibited by the crystal symmetry, so that Cu 3d-electrons can only become delocalized through hybridization with other more itinerant bands, resembling that in …
In this work we report the physical properties of the new intermetallic compound TbRhIn5 investigated by means of temperature dependent magnetic susceptibility, electrical resistivity, heat-capacity and resonant x-ray magnetic diffraction experiments. TbRhIn5 is an intermetallic compound that orders antiferromagnetically at TN = 45.5 K, the highest ordering temperature among the existing RRhIn5 (1-1-5, R = rare earth) materials. This result is in contrast to what is expected from a de Gennes scaling along the RRhIn5 series. The X-ray resonant diffraction data below TN reveal a commensurate ant…
We present a systematic study of the structure, electronic, and magnetic properties of a new branch of intermetalllic compounds, $R$V$_6$Sn$_6$ ($R$ = Tb - Tm) by using X-ray diffraction, magnetic susceptibility, magnetization, electrical transport, and heat-capacity measurements. These compounds feature a combination of a non-magnetic vanadium kagome sublattice and a magnetic rare-earth triangular sublattice that supports various spin anisotropies based on different $R$ ions. We find magnetic orders for the $R$ = Tb, Dy, and Ho compounds at 4.4, 3, 2.5 K, respectively, while no ordering is de…
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 …
In intermetallic compounds with zero-orbital momentum ($L=0$) the magnetic anisotropy and the electronic band structure are interconnected. Here, we investigate this connection on divalent Eu and trivalent Gd intermetallic compounds. We find by X-ray magnetic circular dichroism an out-of-plane easy magetization axis in 2D atom-thick EuAu$_2$. Angle-resolved photoemission and density-functional theory prove that this is due to strong $f-d$ band hybridization and Eu$^{2+}$ valence. In contrast, the easy in-plane magnetization of the structurally-equivalent GdAu$_2$ is ruled by spin-orbit-split $…
Temperature dependence of magnetization curves of well homogenized samples of Ce(Co$_{1-x}$Cu$_{x}$)$_5$ ($0\le x \le 0.7$), a family of representative $4f$-$3d$ intermetallic magnets found in rare-earth permanent magnets, is measured. A remarkable enhancement of intrinsic coercivity is observed with $x=0.3$ and $x=0.4$, persisting to higher temperatures. This experimental observation is theoretically attributed to an effect of electronic correlation among $4f$-electrons. That is, an intrinsic pinning happens originating in an anomalously enhanced magnetic anisotropy energy contributed by an o…
The rare-earth pyrosilicate family of compounds (RE$_{2}$Si$_{2}$O$_{7}$) hosts a variety of polymorphs, some with honeycomb-like geometries of the rare-earth sublattices, and the magnetism has yet to be deeply explored in many of the cases. Here we report on the ground state properties of C-Er$_{2}$Si$_{2}$O$_{7}$. C-Er$_{2}$Si$_{2}$O$_{7}$ crystallizes in the C2/m space group and the Er$^{3+}$ atoms form a distorted honeycomb lattice in the $a$-$b$ plane. We have utilized specific heat, DC susceptibility, and neutron diffraction measurements to characterize C-Er$_{2}$Si$_{2}$O$_{7}$. Our spe…
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…
Zn-Paratacamite is a rare spin 1/2 antiferromagnetic insulator with an ideal kagome lattice structure in part of its phase diagram. As a function of Zn doping, this material undergoes a structural distortion which relieves the frustration and introduces magnetic order in the ground state, though the precise nature of the order is not clear at this point. In this paper, we present strong evidence for Neel ordering in the strongly distorted phase of Zn-Paratacamite through the application of quantum Monte-Carlo techniques. These numerical results support a recent Schwinger-boson mean field theor…
In the series R2PdSi3, Nd2PdSi3 is an anomalous compound in the sense that it exhibits ferromagnetic order unlike other members in this family. The magnetic ordering temperature is also unusually high compared to the expected value for a Nd-based system, assuming 4f localization. Here, we have studied the electronic structure of single crystalline Nd2PdSi3 employing high resolution photoemission spectroscopy and ab initio band structure calculations. Theoretical results obtained for the effective electron correlation strength of 6 eV corroborate well with the experimental valence band spectra.…
In this review article we present a survey of unconventional superconductors and their coexistence behaviour with magnetism. We focus on Ce- and U-based heavy fermion superconductors, in addition we discuss the rare earth borocarbide and skutterudite superconductors. We show that heavy fermion behaviour in Ce- and U- compounds should be described differently. While the Kondo-lattice model with localised 4f-electrons is appropriate for Ce-compounds, dual models including localised and itinerant 5f-electrons are necessary for U-compounds. We demonostrate that this leads to consistent results for…
The Schwinger-boson mean-field theory is used to study the three-dimensional antiferromagnetic ordering and excitations in compounds $L_2BaNiO_5$, a large family of quasi-one-dimensional mixed-spin antiferromagnet. To investigate magnetic properties of these compounds, we introduce a three-dimensional mixed-spin antiferromagnetic Heisenberg model based on experimental results for the crystal structure of $L_2BaNiO_5$. This model can explain the experimental discovery of coexistence of Haldane gap and antiferromagnetic long-range order below Néel temperature. Properties such as the low-lying ex…
The results of dc magnetization, electrical and magnetoresistance and heat capacity measurements (2-300 K) on Tb7Rh3, crystallizing in Th7Fe3-type hexagonal structure, are reported. In this compound, magnetic ordering sets in around 90 K with additional transitions at low temperatures and the temperature coefficient of resistivity (R), dR/dT, is negative over a wide temperature range in the paramagnetic state. The present magnetization results reveal that this compound is apparently characterized by rich features in the magnetic-field-temperature phase diagram. A point of major emphasis is tha…
We apply the first-principles density functional theory + dynamical mean field theory framework to evaluate the crystal field splitting on rare earth sites in hard magnetic intermetallics. An atomic (Hubbard-I) approximation is employed for local correlations on the rare earth 4$f$ shell and self-consistency in the charge density is implemented. We reduce the density functional theory self-interaction contribution to the crystal field splitting by properly averaging the 4$f$ charge density before recalculating the one-electron Kohn-Sham potential. Our approach is shown to reproduce the experim…
The search for oxide materials with physical properties similar to the cuprate high Tc superconductors, but based on alternative transition metals such as nickel, has grown and evolved over time. The recent discovery of superconductivity in doped infinite-layer nickelates RNiO2 (R = rare-earth element) further strengthens these efforts.With a crystal structure similar to the infinite-layer cuprates - transition metal oxide layers separated by a rare-earth spacer layer - formal valence counting suggests that these materials have monovalent Ni1+ cations with the same 3d electron count as Cu2+ in…
Magnetization and heat capacity measurements of ternary rare earth intermetallic compound GdNiAl3 demonstrate para to ferromagnetic transition at Tc=165.5K. In addition multiple short range magnetic transitions observed below Tc are suggestive of competing interactions in this compound. As a result of this a weak Griffiths phase type behaviour is observed in the paramagnetic region. This complex behaviour is rather supported by the random orientation of Ni centered tricapped trigonal prisms with additional Al atoms in the structure. Heat capacity and resistivity data display an interesting pea…
We report the thermodynamic, magnetic, and electronic transport properties of the new ternary intermetallic system (Ce,La)3Pt4In13. Ce3Pt4In13 orders antiferromagnetically at 0.95 K while the non-magnetic compound La3Pt4In13 is a conventional 3.3 K superconductor. Kondo lattice effects appear to limit the entropy associated with the Neel transition to (1/4)Rln2 as an electronic contribution to the specific heat of gamma = 1 J/mole-Ce K2 is observed at TN; roughly 35% of this gamma survives the ordering transition. Hall effect, thermoelectric power, and ambient-pressure resistivity measurements…
The role of slight changes of the chemical composition on antiferromagnetic ordering of Cr in rare-earth orthochoromites was investigated on a series of ceramic solid-solutions Ce$_{1-x}$Eu${_x}$O$_3$ where x varied from 0 to 1. Gradual replacement of Ce with Eu reduces the cell volume and acts equivalently to applying external pressure. Full replacement of Ce by Eu, on the other hand, reduces the Néel temperature from 260 K for CeCrO$_3$ to 178 K for EuCrO$_3$ as established by magnetization, heat capacity and neutron powder diffraction measurements. High resolution x-ray powder diffraction m…
High-pressure superconductivity in a rare-earth doped Ca0.86Pr0.14Fe2As2 single crystalline sample has been studied up to 12 GPa and temperatures down to 11 K using designer diamond anvil cell under a quasi-hydrostatic pressure medium. The electrical resistance measurements were complemented by high pressure and low temperature x-ray diffraction studies at a synchrotron source. The electrical resistance measurements show an intriguing observation of superconductivity under pressure, with Tc as high as ~51 K at 1.9 GPa, presenting the highest Tc reported in the intermetallic class of 1-2-2 iron…
We report the NQR study on the pressure-induced paramagnetic state in the antiferromagnetic (AF) intermetallic compound YMn$_2$ with the Néel temperature T_N=100 K at ambient pressure. From the $T$ variation of the nuclear spin-lattice relaxation rate, $^{55}(1/T_1)$ of $^{55}$Mn above the critical pressure of 4 kbar, the spin fluctuation feature is found to change below a temperature $T_{sf}$. At higher temperature than $T_{sf}$, the nuclear relaxation behavior is well described in terms of the self-consistent renomalized (SCR) spin fluctuation theory for nearly AF metals, whereas below $T_{s…
The microscopic description of the CDW phase transition is still debated and remains controversial. The question is how to extend the Peierls picture to real systems in higher dimensions. A general tendency is found in the thermodynamic properties such as the specific heat jump DCp and the decrease of the longitudinal elastic stiffness constant DC11/C11 at the CDW phase transition in several materials, such as quasi-one dimensional (K0.3MoO3), transition metal dichalcogenide compounds (2H-NbSe2), rare earth tritellurides (TbTe3, ErTe3, HoTe3) and intermetallic compound (Lu5Ir4Si10). DCp and DC…
Non-thermal correlations of strongly correlated electron systems and the far-from-equilibrium properties of phases of condensed matter have become a topical research area. Here, an overview of the non-linear dynamics found near continuous zero-temperature phase transitions within the context of effective temperatures is presented. In particular, we focus on models of critical Kondo destruction. Such a quantum critical state, where Kondo screening is destroyed in a critical fashion, is realized in a number of rare earth intermetallics. This raises the possibility of experimentally testing for t…
Quantum Spin Singlet Ground State with Large Excitation Gap in the S = 3/2 quasi-1D van der Waals materials MoX3 (X = I, Br)
University of California, Los Angeles（加州大学洛杉矶分校）；California NanoSystems Institute, University of California, Los Angeles（加州纳米系统研究所，加州大学洛杉矶分校）；University of California, Riverside（加州大学河滨分校）；Auburn University（奥本大学）；University of Georgia（佐治亚大学）；Oak Ridge National Laboratory（橡树岭国家实验室）
本研究发现 MoX3 (X = I, Br) 晶体同时具有量子自旋单态基态和经典 Néel 有序，通过实验与理论计算证实了其一维链内与三维链间耦合的相互作用，为探索原子链极限下的量子磁性提供了独特平台。
Rare earth based intermetallics, SmScGe and NdScGe, are shown to exhibit near zero net magnetization with substitutions of 6 to 9 atomic percent of Nd and 25 atomic percent of Gd, respectively. The notion of magnetic compensation in them is also elucidated by the crossover of zero magnetization axis at low magnetic fields (less than 103 Oe) and field-induced reversal in the orientation of the magnetic moments of the dissimilar rare earth ions at higher magnetic fields. These magnetically ordered materials with no net magnetization and appreciable conduction electron polarization display an att…
The series of intermetallic compounds $R$NiSi$_3$ ($R$ = rare earth) shows interesting magnetic properties evolving with $R$ and metamagnetic transitions under applied magnetic field for some of the compounds. The microscopic magnetic structures must be determined to rationalize such rich behavior. Here, resonant x-ray magnetic diffraction experiments are performed on single crystals of GdNiSi$_{3}$ and TbNiSi$_{3}$ at zero field. The primitive magnetic unit cell matches the chemical cell below the Néel temperatures $T_{N}$ = 22.2 and 33.2 K, respectively. The magnetic structure is determined …
We investigate the magnetic, thermal, and magnetocaloric properties of the intermetallic HoAl$_{3}$ compounds with two different crystal structures. The room-temperature equilibrium trigonal phase HoAl$_{3}$ undergoes an antiferromagnetic (AFM) transition at the Neel temperature $T^{\rm tri}_{\rm N} =$ 9.8 K. The AFM ordering of the compound is strong against the magnetic field, so that inverse magnetocaloric effect (MCE) is found even under a magnetic field change of 0-50 kOe. The high-pressure cubic phase HoAl3, prepared by a rapid-solidification process, is antiferromagnetically ordered bel…
The rare-earth compounds R2O2Bi (R=Tb, Dy, Er, Lu, Y) are newly discovered superconductors in the vicinity of a rare-earth magnetic long-range order. In this work, we determine the magnetic order of the parent compound Dy2O2Te by neutron scattering as the A-type antiferromagnetic structure below the Néel temperature TN=9.7K. The large staggered magnetic moment 9.4(1) μB per Dy at T=3.5K lies in the basal ab plane. In a magnetic field, anomalous magnetic properties including the bifurcation between zero-field- and field-cooling magnetization, a butterfly-shaped magnetic hysteresis, and slow mag…
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 …
We report occurrence of large magnetoresistance in lightly doped antiferromagnetic paraelectric EuTiO3. Reports of magnetoresistance in rare-earth titanates (RTiO3 oxides) are very scarce because they are highly insulating at low temperatures. EuTiO3 is an insulator at 2.5 K and 1% La3+ substitution for Eu2+ lowers the resistivity over five orders of magnitude at 2.5 K. It is shown that Eu0.99La0.01TiO3 which is antiferromagnetic below T= 5.43 K shows large magnetoresistance over a wide temperature. At 2.5 K, magnetoresistance is -42 % for H = 6 kOe and it increases to -75 % for H = 7 T. Even …
The recent discoveries of proximate quantum spin-liquid compounds and their potential application in quantum computing informs the search for new candidate materials for quantum spin-ice and spin-liquid physics. While the majority of such work has centered on members of the pyrochlore family due to their inherently frustrated linked tetrahedral structure, the rare-earth pyrogermanates also show promise for possible frustrated magnetic behavior. With the familiar stoichiometry $RE_2$Ge$_2$O$_7$, these compounds generally have tetragonal symmetry with a rare-earth sublattice built of a spiral of…
The mixed rare-earth orthochromite Nd$_{0.5}$Dy$_{0.5}$CrO$_{3}$ has a Néel temperature ($T_\mathrm{N}$) of ${\sim}$ 175\,K, resulting in the G-type antiferromagnetic ordering of Cr$^{3+}$ spins. The inverse susceptibility shows a deviation from Curie-Weiss law at 230\,K, with a large effective paramagnetic moment of 8.8\,$μ_{\mathrm{B}}$. The ZFC-FC magnetization bifurcate just above $T_\mathrm{N}$ and show a distinct signature of spin reorientation near 60\,K. Neutron diffraction show that below $T_\mathrm{N}$, the Cr$^{3+}$ spins align in $Γ_{2}$ representation as ($F_{x}$, $G_{z}$). Below …
The magnetic phase diagrams of RMnO3 (R = Er, Yb, Tm, Ho) are investigated up to 14 Tesla via magnetic and dielectric measurements. The stability range of the AFM order below the Neel temperature of the studied RMnO3 extends to far higher magnetic fields than previously assumed. Magnetic irreversibility indicating the presence of a spontaneous magnetic moment is found near 50 K for R=Er, Yb, and Tm. At very low temperatures and low magnetic fields the phase boundary defined by the ordering of the rare earth moments is resolved. The sizable dielectric anomalies observed along all phase boundari…
We report the pressure response of charge-density-wave (CDW) and ferromagnetic (FM) phases of the rare-earth intermetallic SmNiC2 up to 5.5 GPa. The CDW transition temperature (T_{CDW}), which is reflected as a sharp inflection in the electrical resistivity, is almost independent of pressure up to 2.18 GPa but is strongly enhanced at higher pressures, increasing from 155.7 K at 2.2 GPa to 279.3 K at 5.5 GPa. Commensurate with the sharp increase in T_{CDW}, the first-order FM phase transition, which decreases with applied pressure, bifurcates into the upper (T_{M1}) and lower (T_c) phase transi…
