The Mn(Bi$_{1-x}$Sb$_x$)$_2$Te$_4$ series is purported to span from antiferromagnetic (AF) topological insulator at x = 0 to a trivial AF insulator at x = 1. Here we report on neutron diffraction and inelastic neutron scattering studies of the magnetic interactions across this series. All compounds measured possess ferromagnetic (FM) triangular layers and we find a crossover from AF to FM interlayer coupling near x = 1 for our samples. The large spin gap at x = 0 closes rapidly and the average FM exchange interactions within the triangular layer increase with Sb substitution. Similar to a previous study of MnBi$_2$Te$_4$, we find severe spectral broadening which increases dramatically across the compositional series. In addition to broadening, we observe an additional sharp magnetic excitation in MnSb$_2$Te$_4$ that may indicate the development of local magnetic modes based on recent reports of antisite disorder between Mn and Sb sublattices. The results suggest that both substitutional and antisite disorder contribute substantially to the magnetism in Mn(Bi$_{1-x}$Sb$_x$)$_2$Te$_4$.
The effect of chemical substitution on the ground state of the geometrically frustrated antiferromagnet CsCrF$_4$ has been investigated through a neutron powder diffraction experiment. Magnetic Fe-substituted CsCr$_{0.94}$Fe$_{0.06}$F$_{4}$ and nonmagnetic Al-substituted CsCr$_{0.98}$Al$_{0.02}$F$_{4}$ samples are measured, and magnetic Bragg peaks are clearly observed in both samples. Magnetic structure analysis revealed a 120$^{\circ}$ structure having a magnetic propagation vector $\mathbf{k}_{\rm mag}=(0,0,1/2)$ in CsCr$_{0.94}$Fe$_{0.06}$F$_{4}$. For CsCr$_{0.98}$Al$_{0.02}$F$_{4}$, a qua…
We discuss the effects of local structure on the electrical transport and magnetic properties of La(0.67)Ca(0.33)Mn(1-x)Ti(x)O(3) system.Based on the intercomparison of the structure, transport and magnetic properties of the Mn site substituted La(0.67)Ca(0.33)MnO(3) with isovalent diamagnetic and paramagnetic ions, we argue that local structural effects have a decisive role to play, compared to the local spin coupling effects, in the ferromagnetic-metallic ground state of the CMR manganites
We examine the possibility of using graphene nanoribbons (GNRs) with directly substituted chromium atoms as spintronic device. Using density functional theory, we simulate a voltage bias across a constructed GNR in a device setup, where a magnetic dimer has been substituted into the lattice. Through this first principles approach, we calculate the electronic and magnetic properties as a function of Hubbard U, voltage, and magnetic configuration. By calculating of the total energy of each magnetic configuration, we determine that initial antiferromagnetic ground state flips to a ferromagnetic s…
A detailed investigation of first order ferrimagnetic (FRI) to antiferromagnetic (AFM) transition in Co (15%) doped $Mn_2Sb$ is carried out. These measurements demonstrate anomalous thermomagnetic irreversibility and glass-like frozen FRI phase at low temperatures. The irreversibility arising between the supercooling and superheating spinodals is distinguised in an ingenious way from the irreversibility arising due to kinetic arrest. Field annealing measurements shows reentrant FRI-AFM-FRI transition with increasing temperature. These measurements also show that kinetic arrest band and superco…
We investigate the interactions between two identical magnetic impurities substituted into a graphene superlattice. Using a first-principles approach, we calculate the electronic and magnetic properties for transition-metal substituted graphene systems with varying spatial separation. These calculations are compared for three different magnetic impurities, manganese, chromium, and vanadium. We determine the electronic band structure, density of states, and Millikan populations (magnetic moment) for each atom, as well as calculate the exchange parameter between the two magnetic atoms as a funct…
The evolution of magnetism and superconductivity in Ce$_2$Rh$_{1-x}$Pd$_x$In$_8$ solid solutions has been studied within the entire concentration range by means of thermodynamic and magnetic measurements at ambient pressure and at temperatures between 0.35 K and room temperature. For this purpose, single crystals with Pd concentrations x = 0, 0.10, 0.15, 0.30, 0.45, 0.55, 0.85 and 1 have been grown from In self-flux and characterized by x-ray diffraction and microprobe analysis. Starting from the antiferromagnet Ce$_2$RhIn$_8$, the Néel temperature gradually decreases with increasing Pd concen…
The mineral barlowite, Cu$_4$(OH)$_6$FBr, has been the focus of recent attention due to the possibility of substituting the interlayer Cu$^{2+}$ site with non-magnetic ions to develop new quantum spin liquid materials. We re-examine previous methods of synthesizing barlowite and describe a novel hydrothermal synthesis method that produces large single crystals of barlowite and Zn-substituted barlowite (Cu$_3$Zn$_x$Cu$_{1-x}$(OH)$_6$FBr). The two synthesis techniques yield barlowite with indistinguishable crystal structures and spectroscopic properties at room temperature; however, the magnetic…
We present a temperature-dependent resonant elastic soft x-ray scattering (REXS) study of the metal-insulator transition in Sr3(Ru1-xMnx)2O7, performed at both Ru and Mn L-edges. Resonant magnetic superstructure reflections, which indicate an incipient instability of the parent compound, are detected below the transition. Based on modelling of the REXS intensity from randomly distributed Mn impurities, we establish the inhomogeneous nature of the metal-insulator transition, with an effective percolation threshold corresponding to an anomalously low x<0.05 Mn substitution.
Non magnetic insulators/semiconductors with induced magnetism introduced via transition metal substitution are one of the promising materials in the field of spintronic, magnetoelectronics and magneto optical devices. In this context, here, we focus on magnetism induced in a non magnetic insulator CaHfO3, by the substitution of 4d element Ru, at Hf site. Structural investigations indicate that substitution of Ru4+ (up to 50%) does not affect the original crystal structure of the parent compound. Magnetic studies divulge a crossover from a diamagnetic to paramagnetic state with 20% Ru substitut…
We have investigated the Mn-site substitution effect in Nd$_{0.45}$Sr$_{0.55}$MnO$_3$ single crystal, which has an $A$-type layered antiferromagnetic ($A$-AFM) phase with the 3$d_{x^2-y^2}$-type orbital-order. Substitution of Fe or Ga for Mn-site suppresses both the $A$-AFM order and competing ferromagnetic (FM) correlation whereas Cr substitution suppresses only the $A$-AFM order but reactivates the underlying FM correlation via double-exchange mechanism along the AFM coupled $c$-direction. In Nd$_{0.45}$Sr$_{0.55}$Mn$_{0.95}$Cr$_{0.05}$O$_3$, the $A$-AFM state with the orbital-order is chang…
We present an investigation into the structural and magnetic properties of Zn-substituted Cu$_{2}$OSeO$_{3}$, a system in which the skyrmion lattice (SkL) phase in the magnetic field-temperature phase diagram was previously seen to split as a function of increasing Zn concentration. We find that splitting of the SkL is only observed in polycrystalline samples and reflects the occurrence of several coexisting phases with different Zn content, each distinguished by different magnetic behaviour. No such multiphase behaviour is observed in single crystal samples.
The magnetic and structural properties of polycrystalline Co$_{4-x}$ Ni$_x$ Nb$_2$ O$_9$ (x=1,2) have been investigated by neutron powder diffraction, magnetization and heat capacity measurements, and density functional theory (DFT) calculations. For x=1, the compound crystallizes in the trigonal P$\bar{3}$c1 space group. Below T$_N$ = 31 K it develops a weakly non-collinear antiferromagnetig structure with magnetic moments in the ab-plane. The compound with x=2 has crystal structure of the orthorhombic Pbcn space group and shows a hard ferrimagnetic behavior below T$_C$ =47 K. For this compou…
To verify the effect of geometrical frustration, we artificially distort the triangular lattice of quasi-two-dimensional organic conductor $κ$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ [BEDT-TTF: bis(ethylenedithio)terathiofulvalene] by analogous-molecular substitution and apply $^{13}$C NMR of bulk and substituted sites, electric conductivity, and static magnetic susceptibility measurements. The results indicate that the magnetic characteristics of the substituted sample are quantitatively similar to those of the pure sample. Moreover the magnetic characteristics at the substituted sites are also the same…
We have investigated magnetic, electrical and thermal transport properties (Seebeck effect and thermal conductivity) of LaSr$_{2}$Mn$_{2-y}$Cr$_{y}$O$_{7}$ polycrystalline samples ($y$=0.1, 0.2, 0.4 and 0.6). The Cr$^{3+}$ substitution for Mn$^{3+}$ sites causes a removal of $d_{x^2-y^2}$ orbital of $e_g$-electron resulting in a volume shrinkage of lattice. Magnetic measurements reveal the appearance of a glassy behavior for Cr-doped samples, accompanied by both a collapse of the A-type antiferromagnetic structure and the growth of ferromagnetic clusters. Cr-doping effect on electrical transpo…
75As NMR experiments were performed in Ba(Fe1-xRux)2As2 for x=0 to 80%. Magnetic fractions and NMR lineshapes demonstrate that Ru substitution destroys the antiferromagnetic (AF) order inhomogeneously with a magnetic moment distributed from 0.9 to 0 uB. Superconductivity emerges at intermediate Ru doping and coexists with AF order only in the regions where moments are smaller than ~0.3uB, resulting in an original nanoscale texture. This situation contrasts with that of Co substitution, challenging the apparent universality of the phase diagram in Fe-based superconductors.
In this study, we investigate the isolated magnetic interactions between two identical Fe atoms divacantly-substituted into graphene. Using density functional theory, we simulated the electronic and magnetic properties for a supercell of graphene with spatial variation of the Fe atoms along either the armchair or zig-zag directions. Overall, we find that the exchange interaction between the two Fe atoms fluctuates from ferromagnetic to antiferromagnetic as a function of the spatial distance in the armchair direction. Given the induced magnetic moment and increased density of states at the Ferm…
We have performed a systematic angle-resolved photoemission study of chemically substituted cuprates Bi$_{2}$Sr$_{2-x}$Bi$_{x}$CuO$_{6+δ}$. We observed that the Fermi surface area shrinks linearly with Bi substitution content $x$, reflecting the electron doping nature of this chemical substitution. In addition, the spectral linewidth broadens rapidly with increasing $x$, and becomes completely incoherent at the superconducting-insulating boundary. The d-wave-like normal-state gap observed in the lightly underdoped region gradually evolves into a large soft gap, which suppresses antinodal spect…
The effect of Co on the structural, magnetic and magnetocaloric effect (MCE) of Ni50-xCoxMn38Sb12 (x=0,2,3,4,5) Heusler alloys was studied. Using x-ray diffraction, we show the evolution of the martensitic phase from the austenite phase. The martensitic transition temperature is found to decrease monotonically with Co concentration. Remarkable enhancement of MCE is observed near room temperature upon Co substitution. The maximum magnetic entropy change of 34 Jkg-1K-1 was achieved in x=5 at 262 K in a field of 50 kOe and a value of 29 Jkg-1K-1 found near room temperature. The significant increa…
Investigating LaNi(1-x)M(x)O3 (M = Mn and Fe), we identify a characteristic evolution of the spectral function with increasing disorder in presence of strong interaction effects across the metal-insulator transition. We discuss these results vis-a-vis existing theories of electronic structure in simultaneous presence of disorder and interaction.
In contrast to SrFe2As2, where only the iron possesses a magnetic moment, in EuFe2As2 an additional large, local magnetic moment is carried by Eu2+. Like SrFe2As2, EuFe2As2 exhibits a spin-density wave transition at high temperatures, but in addition the magnetic moments of the Eu2+ order at around 20 K. The interplay of pressure-induced superconductivity and the Eu2+ order leads to a behavior which is reminiscent of re-entrant superconductivity as it was observed, for example, in the ternary Chevrel phases or in the rare-earth nickel borocarbides. Here, we study the delicate interplay of the …
We investigate the doping-induced changes in the electronic structure of CeB$_6$ on a series of substituted Ce$_{1-x}R_x$B$_6$ samples ($R$ = La, Nd) using diffuse neutron scattering. We observe a redistribution of magnetic spectral weight across the Brillouin zone, which we associate with the changes in the Fermi-surface nesting properties related to the modified charge carrier concentration. In particular, a strong diffuse peak at the corner of the Brillouin zone ($R$ point), which coincides with the propagation vector of the elusive antiferroquadrupolar (AFQ) order in CeB$_6$, is rapidly su…
Spin correlations in the overdoped region of Bi1.75Pb0.35Sr1.90CuO6+z have been explored with Fe-doped single crystals characterized by neutron scattering, muon-spin-rotation (muSR) spectroscopy, and magnetic susceptibility measurements. Static incommensurate spin correlations induced by the Fe spins are revealed by elastic neutron scattering. The resultant incommensurability delta is unexpectedly large (~0.2 r.l.u.), as compared with delta ~ 1/8 in overdoped superconductor La2-xSrxCuO4. Intriguingly, the large delta in this overdoped region is close to the hole concentration p. This result is…
We report the structural, magnetic, transport and electronic properties of Nb substituted LaCo$_{1-x}$Nb$_x$O$_3$ ($x =$ 0--0.2). The Rietveld analysis of x-ray diffraction data demonstrate structural phase transitions from rhombohedral to orthorhombic and further to monoclinic with increasing the Nb concentration up to $x \ge$ 0.2. Interestingly, we observed dramatic changes in the magnetization (M) with increasing the Nb concentration, as the M sharply increases below 10~K even at 2.5\% substitution. Furthermore, ac susceptibility data show the spin-glass behavior in $x=$ 0.1 sample. We find…
We report the results of de-Haas-van-Alphen (dHvA) measurements in Cd doped CeCoIn$_5$ and LaCoIn$_5$. Cd doping is known to induce an antiferromagnetic order in the heavy fermion superconductor CeCoIn$_5$, whose effect can be reversed with applied pressure. We find a slight but systematic change of the dHvA frequencies with Cd doping in both compounds, reflecting the chemical potential shift due to the addition of holes. The frequencies and effective masses are close to those found in the nominally pure compounds with similar changes apparent in the Ce and La compounds with Cd substitution. W…
Using angle-resolved photoemission spectroscopy, we studied the electronic structure of NaFe$_{1-x}$Co$_x$As from an optimally doped superconducting compound ($x=0.028$) to a heavily overdoped non-superconducting one ($x=0.109$). Similar to the case of "122" type iron pnictides, our data suggest that Co dopant in NaFe$_{1-x}$Co$_x$As supplies extra charge carriers and shifts the Fermi level accordingly. In the $x=0.109$ compound, the hole-like bands around the zone center $Γ$ move to deeper binding energies and an electron pocket appears instead. The overall band renormalization remains basica…
The occurrence of bulk superconductivity at ~22 K is reported in polycrystalline samples of BaFe2-xRuxAs2 for nominal Ru content in the range of x=0.75 to 1.125. A systematic suppression of the spin density wave transition temperature (TSDW) precedes the appearance of superconductivity in the system. A phase diagram is proposed based on the measured TSDW and superconducting transition temperature (TC) variations as a function of Ru composition. Band structure calculations, indicate introduction of electron carriers in the system upon Ru substitutiom. The calculated magnetic moment on Fe shows …
Magnetic skyrmions are nano-sized topological spin textures stabilized by a delicate balance of magnetic energy terms. The chemical substitution of the underlying crystal structure of skyrmion-hosting materials offers a route to manipulate these energy contributions, but also introduces additional effects such as disorder and pinning. While the effects of doping and disorder have been well studied in B20 metallic materials such as Fe$_{1-x}$Co$_x$Si and Mn$_{1-x}$Fe$_x$Si, the consequences of chemical substitution in the magnetoelectric insulator Cu$_2$OSeO$_3$ have not been fully explored. In…
Single crystals of SrFe2-xPtxAs2 (0 < x < 0.36) were grown using the self flux solution method and characterized using x-ray crystallography, electrical transport, magnetic susceptibility, and specific heat measurements. The magnetic/structural transition is suppressed with increasing Pt concentration, with superconductivity seen over the range 0.08 < x < 0.36 with a maximum transition temperature Tc of 16 K at x = 0.16. The shape of the phase diagram and the changes to the lattice parameters are similar to the effects of other group VIII elements Ni and Pd, however the higher transition tempe…
Studies connected with the investigations of non-Fermi liquid (NFL) systems continue to attract interest in condensed matter physics community. Understanding the anomalous physical properties exhibited by such systems and its related electronic structures is one of the central research topics in this area. In this context, Ce-based and Ce-site diluted (with non-magnetic ions) compounds provide a fertile playground. Here, we present a detailed study of non-linear DC susceptibility and combined density functional theory plus dynamical mean field theory (DFT+DMFT) on Ce0.24La0.76Ge. Theoretical i…
The emergence of a ferromagnetic component in $LaMnO_{3}$ with low Cr-for-Mn substitution has been studied by x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Mn and Cr K edges. The local magnetic moment strength for the Mn and Cr are proportional to each other and follows the macroscopic magnetization. The net ferromagnetic components of $Cr^{3+}$ and $Mn^{3+}$ are found antiferromagnetically coupled. Unlike hole doping by La site substitution, the inclusion of $Cr^{3+}$ ions up to x = 0.15 does not decrease the Jahn-Teller (JT) distortion and consequently does not s…
5d iridates have shown vast emergent phenomena due to a strong interplay among its lattice, charge and spin degrees of freedom, because of which the potential in spintronic application of the thin-film form is highly leveraged. Here we have epitaxially stabilized perovskite SrIr$_{0.8}$Sn$_{0.2}$O$_3$ on [001] SrTiO$_3$ substrates through pulsed laser deposition and systematically characterized the structural, electronic and magnetic properties. Physical properties measurements unravel an insulating ground state with a weak ferromagnetism in the compressively strained epitaxial film. The octah…
We report the results of a study of the Hall effect and magnetoresistance in single crystals of Sr2RuO4 in which Sr^(2+) has been substituted by La^(3+) (Sr(2-y)La(y)RuO(4)) or Ru^(4+) by Ti^(4+) (Sr(2)Ru(1-x)Ti(x)O(4)). For undoped Sr2RuO4, the purity is so high that the strong-field Hall coefficient can be measured for fields above 4 T. The conventional weak-field Hall coefficient as a function of doping shows a sharp jump and sign change at y ~ 0.01 that is unrelated to either a sharp change in Fermi-surface topography or a magnetic instability. The implications of these results are discuss…
Room temperature ferromagnetism was characterized for thin films of SrTi$_{0.6}$Fe$_{0.4}$O$_{3-δ}$ grown by pulsed laser deposition on SrTiO$_{3}$ and Si substrates under different oxygen pressures and after annealing under oxygen and vacuum conditions. X-ray magnetic circular dichroism demonstrated that the magnetization originated from Fe$^{2+}$ cations, whereas Fe$^{3+}$ and Ti$^{4+}$ did not contribute. Films with the highest magnetic moment (0.8 μB per Fe) had the highest measured Fe$^{2+}$:Fe${^3+}$ ratio of 0.1 corresponding to the largest concentration of oxygen vacancies (δ = 0.19). …
We report the structural and magnetic characterization of La-substituted Gd$_{1-x}$La$_x$RhIn$_5$ ($x\leq$ 0.50) antiferromagnetic (AFM) compounds. The magnetic responses of pure GdRhIn$_5$ are well described by a $S=7/2$ Heisenberg model. When Gd$^{3+}$ ions are substituted by La$^{3+}$, the maximum of the susceptibility and the inflection point of the magnetic specific heat are systematically shifted to lower temperatures accompanied by a broadening of the transition. The data is qualitatively explained by a phenomenological model which incorporates a distribution of magnetic regions with di…
We report an impurity effect in the organic superconductor $κ$-(ET)$_2$Cu(NCS)$_2$ by substitution of the ET molecule with an analogue, bis(methyleneditio)tetrathiafulvalene (MT). The superconducting transition temperature decreases with increasing substitution. The in-plane magnetic penetration depth is enhanced with substitution, which is quantitatively attributed to the decrease in the in-plane mean free path. The enhancement of the penetration depth can also explain the reduction of the effective pinning in terms of the condensation energy.
The influence of La non magnetic impurities on the spin dynamics of CeCoIn$_{5}$ was studied by inelastic neutron scattering. In La-substituted systems, the spin resonance peak (observed at $Ω_{res}=0.55 meV$ in the pure system) is shifted to lower energies but the ratio $Ω_{res}/k_{B}T_{c}$ remains unchanged. The excitation broadens till it reaches 0.3 meV equal to the value of the quasi-elastic signal in the normal state. The evolution of La substitution is compared with the evolution of the magnetic resonance in Ni and Zn substituted YBa$_{2}$Cu$_{3}$O$_{7}$.
Sr substituted perovskites La1.8Sr0.2MMnO6 (M = Ni, Co) were synthesized using solid state reaction technique to present a systematic study on their morphological, structural and magnetic properties. The average grain size of the as-prepared La1.8Sr0.2NiMnO6 samples are in the range of 0.2-0.7 μm and those for La1.8Sr0.2CoMnO6 manganites are 0.1-2.8 μm, which is significantly less than that of unsubstituted La2NiMnO6 (LNMO) and La2CoMnO6 (LCMO) manganites. The XPS analysis enlightened about phase purity, binding energy and oxygen vacancy of La1.8Sr0.2MMnO6 manganites. The Sr substituted LNMO h…
Chemical substitution is commonly used to explore new ground states in materials, yet the role of disorder is often overlooked. In Mn-substituted BaFe$_{2}$As$_{2}$ (MnBFA), superconductivity (SC) is absent, despite being observed for nominal hole-doped phases. Instead, a glassy magnetic phase emerges, associated with the $S=5/2$ Mn local spins. In this work, we present a comprehensive investigation of the electronic structure of MnBFA using angle-resolved photoemission spectroscopy (ARPES). We find that Mn causes a small and orbital-specific reduction of the electron pockets, only partially d…
A series of in-plane substituted compounds, including Cu-site (SrZn$_x$Cu$_{2-x}$(BO$_3$)$_2$), and B-site (SrCu$_2$(Si$_x$B$_{1-x}$O$_3$)$_2$) substitution, were synthesized by solid state reaction. X-ray diffraction measurements reveal that these compounds are single-phase materials and their in-plane lattice parameter depends systematically on the substituting content $x$. The magnetic susceptibility in different magnetic fields, the magnetization at different temperatures, and the resistivity at room temperature were measured, respectively. It is found that the spin gap deduced from the ma…
We report on a microscopic study of the evolution of ferromagnetism in the Ru substituted ferromagnetic superconductor (FM SC) UCoGe crystallizing in the orthorhombic TiNiSi-type structure. For that purpose, two single crystals with composition UCo0.97Ru0.03Ge and UCo0.88Ru0.12Ge have been prepared and characterized by magnetization, AC susceptibility, specific heat and electrical resistivity measurements. Both compounds have been found to order ferromagnetically below TC = 6.5 K and 7.5 K, respectively, which is considerably higher than the TC = 3 K of the parent compound UCoGe. The higher va…
We show that Pr${_{0.5}}$Ca$_{0.5}$MnO${_3}$ with 2.5% Al substitution and La${_{0.5}}$Ca$_{0.5}$MnO${_3}$ (LCMO) exhibit qualitatively similar and visibly anomalous M-H curves at low temperature. Magnetic field causes a broad first-order but irreversible antiferromagnetic (AF)-insulating (I) to ferromagnetic (FM)-metallic (M) transition in both and gives rise to soft FM state. However, the low temperature equilibrium state of Pr$_{0.5}$Ca$_{0.5}$Mn$_{0.975}$Al$_{0.025}$O$_3$ (PCMAO) is FM-M whereas that of LCMO is AF-I. In both the systems the respective equilibrium phase coexists with the ot…
We report the structure, magnetic, and thermal property measurements on single crystalline and polycrystalline samples of Ru substituted honeycomb lattice iridate Na$_2$Ir$_x$Ru$_{1-x}$O$_3$ (x = 0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.5). The evolution of magnetism in Na$_2$Ir$_x$Ru$_{1-x}$O$_3$ has been studied using dc and ac magnetic susceptibility, and heat capacity measurements. The parent compound Na$_2$IrO$_3$ is a spin-orbit driven Mott insulator with magnetic order of reduced moments below $T_N = 15$~K\@. In the Ru substituted samples the antiferromagnetic long range state is replaced by a s…
The compound, Sr3NiPtO6, belonging to a K4CdCl6-type rhombohedral structure, has been reported not to exhibit magnetic ordering at least down to 1.8 K, despite a relatively large value of paramagnetic Curie temperature. This is attributable to geometrical frustration. Here we report the results of our efforts to gradually replace Sr by Ba and to probe the influence of positive (external) and negative (chemical) pressure on the magnetic behavior of this compound. In the Ba substituted series, single phase is formed up to x= 1.0 with Ba substituting for Sr. The magnetic properties of the parent …
We discuss here a comparative study of the role of local structure and/or nature of local magnetic coupling on the electrical transport properties of Mn site substituted La-Ca-Mn-O perovskites. Particular emphasis is being paid to explore the strong correlation between the insulator-metal transition (TIM) and the residual resistivity (rhoo) upon substitution. There exists an inverse relationship between ro and TIM in the compounds under present discussion. Best fit for TIM Vs ro could be obtained for the compounds understudy to a first order exponential decay with a functional form TIM = TIMO …
We present a temperature-dependent x-ray absorption (XAS) and resonant elastic x-ray scattering (REXS) study of the metal-insulator transition (MIT) in Sr3(Ru1-xMnx)2O7. The XAS results reveal that the MIT drives the onset of local antiferromagnetic correlations around the Mn impurities, a precursor of the long-range antiferromagnetism detected by REXS at T_order<T_MIT. This establishes that the MIT is of the Mott-type (electronic correlations) as opposed to Slater-type (magnetic order). While this behavior is induced by Mn impurities, the (1/4,1/4,0) order exists for a wide range of Mn concen…
We use neutron diffraction, magnetometry and low temperature heat capacity to probe giant magneto-elastic coupling in CoMnSi-based antiferromagnets and to establish the origin of the entropy change that occurs at the metamagnetic transition in such compounds. We find a large difference between the electronic density of states of the antiferromagnetic and high magnetisation states. The magnetic field-induced entropy change is composed of this contribution and a significant counteracting lattice component, deduced from the presence of negative magnetostriction. In calculating the electronic entr…
