Anomalous magnetic susceptibility of Y 2Fe 3Si 5

FeCl3 intercalated graphite compounds exhibit a sharp maximum in magnetic susceptibility at 1.7K. By using Mossbauer spectroscopy as a characterisation tool, the authors show that this peak is dramatically enhanced as the number of iron vacancies in the intercalant lattice is increased. These results strongly suggest that the sharp susceptibility maximum is due to a spin glass transition where the iron vacancies inhibit long-range magnetic order, thus providing a new series of compounds to help elucidate the many unknown properties of the spin glass state.

The relationship between structural and electronic phase transitions in V2O3 thin films is of critical importance for understanding of the mechanism behind metal–insulator transition (MIT) and related technological applications. Despite being extensively studied, there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far. Using V2O3 thin films grown on r-plane Al2O3 substrates, which exhibit abrupt MIT and structural phase transition, we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements. Our result provides experimental evidence for clarifying this issue, which could form the basis of theoretical studies as well as technological applications in V2O3.

The effect of pressure and magnetic field on the O–R structural phase transition in La 1−xSr xMnO 3 single crystals: the transition heat

We have prepared a series of BEDT‐TTF or BETS‐based radical‐cation salts (D)4MBr4(C6H6–nXn) with tetrahedral anions [MIIBr4]2– (D = BETS, BEDT‐TTF; X = F, Cl, Br; n = 1, 2). The salts (D)4MBr4(C6H6–nXn) are characterized by the different structures of neighboring conducting layers, structural phase transitions, and different types of conductivity, namely, metallic and semiconducting, along and across the conducting layers, respectively. The Fermi surface of the metallic layer of (D)4MBr4(C6H6–nXn) with alternating crystallographically different conducting layers (dual‐layered salts) provides a roadmap for interpreting the transport properties of quasi‐two‐dimensional organic conductors. This review reports on the structures of these compounds, the effect of MBr4 anions and solvent on the occurrence of phase transitions, different Fermi surface topologies in connection with the different structures of neighboring conducting layers, and the possibility of the incoherent transport of charge carriers in such systems.

The magnetic susceptibility of the upper soil horizons in the city of Moscow was studied by the itinerary, key, and transect methods. Statistical regularities were found for the magnetic susceptibility of soils developed under urban conditions. Kappametric measurements can be used for the rapid detection of technogenically contaminated soils on large (the whole city) and small (separate plots) areas of the territory studied. The delineation of areas on the basis of their magnetic susceptibility (minimum, maximum, and average values) was proposed for mapping contaminated territories.

Ground state, structural, and magnetic phase transitions of strained BiVO3 were investigated using the first-principles calculation based on the self-interaction corrected local density approximation + U functional. The calculated total energy indicated that the ground state structure for BiVO3 was a monoclinic P21/a phase and ferromagnetic ordering is predicted to be the magnetic ground state. Furthermore, it was found that BiVO3 are metastable compounds under strain effects, where several structural phase transitions were predicted from the monoclinic P 21 / a phase to the orthorhombic P b n m phase (at compressive volumetric strain) and to monoclinic C m and C c phases (at expansive volumetric strain). Furthermore, calculations on electronic band structure and density of states for the monoclinic P21/a phase and the monoclinic C c phase of BiVO3 with ferromagnetic ordering were conducted. The calculated band structure predicted a small energy gap with a direct energy bandgap of 0.456 eV and an indirect energy gap of 0.466 eV. Interestingly, the obtained results revealed that the BiVO3 calculated density of states exhibited Mott-Hubbard insulator type. Therefore, the ground state monoclinic C c phase of strained BiVO3 with ferromagnetic ordering is suggested as a new candidate for multiferroic materials at room temperature and a visible light driven photocatalytic/photovoltaic effect. The obtained results in this study could provide valuable theoretical information on BiVO3 under strain effects, which could open new opportunities for future research and technological applications.

The adsorption and desorption of hydrogen, oxygen, carbon monoxide, and ethylene on Ni(110) and of hydrogen on Ni(100) were monitored with He-atomic beam scattering. The attenuation of the specular beam during gas adsorption initially shows a linear dependence on the adsorbate partial pressure and dose, which, when extrapolated, corresponds to a decrease of 100% for about one-half a Langmuir (1 L=1.33×10−4 Pa s). This can be related to total collision cross sections of the adsorbed particles in the range of 30 to 100 Å2, indicating dominance of the attractive interaction of the He atoms with adsorbates in dilute concentrations. Statistical occupation or depletion of sites in the adlayer structures suffice to explain the changes in coherent specular intensity upon adsorption and desorption processes. Near the Curie temperature of Ni (Tc=631 K), diffracted intensities of H2 and He show non-Debye–Waller behavior in their temperature dependence. Connections to changes in carbon surface concentration and to a (structural) phase transition (‘‘surface roughening’’) near Tc are discussed.

Coupling lattice and spin degrees of freedom without the use of external magnetic fields allows for energy-efficient spintronic devices. In this context, hybrid materials composed of an oxide layer undergoing a first-order, structural phase transition (SPT), such as V2O3, and a ferromagnetic layer, such as Ni, constitute a very promising paradigm for the development of such applications. In the case of a Ni/V2O3 heterostructure, the structural domains inherent to the first-order phase transition in the V2O3 cause a differential strain pattern in the Ni layer. By virtue of the inverse magnetorestrictive effect, this strain pattern is converted into a magnetic anisotropy distribution in the Ni. This offers a promising alternative to voltage-controlled magnetism or other switching mechanisms without a magnetic field [1,2].Here we show by direct imaging of the thermal evolution of the Ni spin structure that the magnetic domains can be tuned in both size and orientation upon crossing the structural phase transition (SPT) of the proximal V2O3 layer [3]. We find a drastic temperature-driven reorientation of the Ni magnetic domains across the SPT which is responsible for an abrupt increase in the coercive field (up to 500%). By synchrotron-based X-ray microscopy we show a reconfiguration of the ferromagnetic domain pattern in the Ni layer across the V2O3 SPT together with changes in magnitude and direction of the magnetic anisotropy. These observations are in good agreement with both angular dependent ferromagnetic resonance measurements and micromagnetic simulations. Our simulations successfully replicate the change in the coercivity as well as the reorientation of the magnetization of the Ni domains after the implementation of a simple model of strain-dependent magnetic anisotropies. Furthermore, simulations also exhibit a phase coexistence of different magnetic domains across the SPT in the V2O3. Direct observations of the lateral correlation length of the Ni domains show an increase of almost an order of magnitude at the SPT compared to room temperature as well as a broad spatial distribution of the local transition temperatures. This corroborates the phase coexistence of Ni anisotropies due to the V2O3 structural domains coexistence across the SPT. Our data reveal that the reorientation of Ni domains is controlled by the reconfiguration of the structural domains of the oxide layer across the SPT [4,5], due to strain induced proximity.Our findings reveal a novel pathway to control magnetic domains without a magnetic field through proximity to a material undergoing a first-order structural phase transition, which allows for engineering of coercive fields for novel data storage architectures and novel device concepts based on “straintronics”. Acknowledgements:This work was supported by the Spanish MINECO projects MAT2015-68772-P and PGC2018-097789-B-I00 and European Union FEDER funds. A.F.R. and M.G.M acknowledge financial support from the EU CALIPSO Transnational Access programme. J.G.R. acknowledges support from Colciencias under grant 120471250659. The work by I.V., C.W. and I.K.S. at UCSD were supported by the Office of Basic Energy Science, U.S. Department of Energy, BES-DMS funded by the Department of Energy’s Office of Basic Energy Science, DMR under grant DE FG02 87ER-45332. **

This study reports the observation of ferromagnetic (FM) order in the non--Au-based approximant crystals (ACs) using an approach whereby a total electron-per-atom ($e/a$) ratio of the spin-glass ${\mathrm{Ga}}_{50}{\mathrm{Pd}}_{36}{\mathrm{Gd}}_{14}$ 1/1 AC is lowered by simultaneously substituting certain ratios of a trivalent Ga and a zero-valent Pd by a monovalent Au. The emergence of FM order by this method was confirmed via magnetic susceptibility, magnetization, and specific-heat measurements. The findings of this study open up opportunities in developing long-range magnetic orders from stoichiometric ACs, quasicrystals, and even other (Ruderman--Kittel--Kasuya--Yosida) RKKY compounds with spin-glass ground state.

We study the momentum- and temperature dependencies of magnetic susceptibilities and magnetic exchange in paramagnetic fcc iron by a combination of density functional theory and supercell dynamical mean-field theory (DFT+DMFT). We find that in agreement with experimental results the antiferromagnetic correlations with the wave vector close to $(0,0,2\pi)$ dominate at low temperatures (as was also obtained previously theoretically), while the antiferromagnetic and ferromagnetic correlations closely compete at the temperatures $T\sim 1000$ K, where $\gamma$-iron exists in nature. Inverse staggered susceptibility has linear temperature dependence at low temperatures, with negative Weiss temperature $\theta_{\rm stagg} \approx -340$ K; the inverse local susceptibility is also linear at not too low temperatures, showing well formed local moments. Analysis of magnetic exchange shows that the dominant contribution comes from first two coordination spheres. In agreement with the analysis of the susceptibility, the nearest-neighbor exchange is found to be antiferromagnetic at low temperatures, while at temperature of the $\alpha$-$\gamma$ structural phase transition its absolute value becomes small, and the system appears on the boundary between the regimes with strongest antiferro- and ferromagnetic correlations.

Superparamagnetism in a RE-compound

We report a comprehensive x-ray scattering study of the low-temperature orthorhombic (LTO)–high-temperature tetragonal (HTT) structural phase transition in 1% iron-doped La2−xSrxCuO4 (x = 0.2). The superlattice (032) peak intensity and the width are investigated in detail for a wide temperature range. We found that the structural phase transition is not sharp and the tilt ordering of the CuO6 octahedra persists above the transition temperature TS (≈77 K). Even at room temperature, the superlattice peak is still observable. The structural phase transition is identified as an order–disorder type phase transition. We found that the tilt ordering in our iron-doped material is always short-ranged, and in the HTT phase the correlation between the tilts along the b axis is better preserved than that along the a axis. Moreover, we identify the role of the Fe as the nucleation centers of the LTO domains in the structural phase transition.

Abstract: The present paper addresses the activation energy and magnetic susceptibility in samarium sulfide (SmS) under the influence of pressure at constant temperature. The samarium sulfide has shown the pressure-induced NaCl (B1) to CsCl (B2) structural phase transition. In this transition, 4f energy level (valence band) of samarium sulfide has shifted towards the 5d conduction band within the band gap. The calculated values of magnetic susceptibility, activation energy and energy-band gap are in close agreement with the experimental results. Keywords: Activation energy, Magnetic susceptibility, Samarium sulfide.

Investigation of Li-induced structural disorder and phase transition in ZnO by Raman spectroscopy

Magnetic properties and structural phase transition in ultrathin fcc Fe(111) and bcc Fe(111) films: First-principles study