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GdFe₀.₅Cr₀.₅O₃ (GFCO) is a single-phase magnetoelectric multiferroic at temperatures close to ambient. Epitaxial thin films of this orthorhombic perovskite would offer the possibility of tuning its electrical and magnetic properties through control of strain and interface effects. Here, 200 nm thick GFCO thin films have been grown on (001) SrTiO3 substrates by solution synthesis and the microstructures have been investigated by cross-sectional transmission electron microscopy. The GFCO films are epitaxial but exhibit a mixture of three different orientation relationships in the form of domains ≈50 nm in diameter. Geometric analyses of the lattice matching show that the misfits for these domains would be tensile with magnitudes of less than 2 %. Pockets of a SrCrO4 reaction product form at the film/substrate interface and do not exhibit any simple orientation with the adjacent phases. The product morphology indicates that the outward diffusion of Sr is more rapid than the inward diffusion of Cr, and this is related to the microstructures of the surrounding phases. These data show that epitaxial films of GFCO can be obtained via this route, but careful control of process parameters would be required to produce single-domain films, and alternate substrates or buffer layers would be needed to inhibit SrCrO4 formation. 

Scanning superconducting quantum interference device (SQUID) microscopy is a powerful tool to study a wide variety of magnetic phenomena including weak magnetism originating from interfaces or antiferromagnets. Many SQUID microscopies utilize piezoelectric “s-bender” designs which offer large scan areas but can be sensitive to vibrations. Here, we design a new cryogenic scanner based off modular sets of double piezoelectric bimorphs which have higher resonant frequencies than “s-bender” designs while maintaining a 160 × 160 μm2 scan area. We demonstrate scanning capabilities by imaging local magnetic flux and susceptibility of an antiferromagnetic EuTiO3 thin film. This design provides extremely sensitive magnetic measurements and is readily adaptable for applications in other scanning probe techniques. 

Canted antiferromagnets GdCrO3 and GdFeO3 have drawn extensive attention due to large magnetoelectric effects, although low temperature multiferroic ordering currently limits possible applications. Iron substitution into GdCrO3 increases both antiferromagnetic and ferroelectric transition temperatures. Room temperature magnetoelectric coupling in a single-phase material has yet to be realized. Here, we report the synthesis of a strained GdFe0.5Cr0.5O3 thin film grown on SrTiO3 and investigation of magnetic domain structure and temperature dependence with scanning superconducting quantum interference device (SQUID) microscopy. Magnetic domain structure remains above 70 K although magnetization of the domain dramatically decreases, which is consistent with bulk hysteresis measurements, in contrast to unstrained samples previously studied. Our results suggest strain tuning Dzyaloshinskii-Moriya interactions in GdFe0.5Cr0.5O3 offers a route to control multiferroic properties in this family of materials. 

Transition-metal dichalcogenides host a variety of charge-density-wave phases that couple lattice, charge, and correlation effects. In 1T -TaS2, the commensurate and nearly commensurate states are well characterized, yet the transition near 350 K into the incommensurate phase has lacked direct momentum-resolved insight. Here, we use temperature-dependent angle-resolved photoemission spectroscopy to track the electronic structure across this transition. We observe a suppression of quasiparticle spectral weight at the Brillouin-zone center, coincident with the transport anomaly, but without clear evidence of a full band-gap opening. The transition appears to involve momentum-dependent redistribution of spectral weight, consistent with a loss of coherence that reshapes the Fermi surface while leaving conduction dispersions largely intact. These results suggest that the nearly commensurate–incommensurate transition may not align with a conventional metal-insulator transition picture, but rather as an electronic reconstruction driven by loss of coherence. Our work provides new microscopic insight into the resistivity anomaly near room temperature and may guide design principles for collective electronic switching in transition-metal dichalcogenides 

Quantum materials have a fascinating tendency to manifest novel and unexpected electronic states upon proper manipulation. Ideally, such manipulation should induce strong and irreversible changes and lead to new relevant length scales. Plastic deformation introduces large numbers of dislocations into a material, which can organize into extended structures and give rise to qualitatively new physics as a result of the huge localized strains. However, this approach is largely unexplored in the context of quantum materials, which are traditionally grown to be as pristine and clean as possible. Here we show that plastic deformation induces robust magnetism in the quantum paraelectric SrTiO3, a property that is completely absent in the pristine material. We combine scanning magnetic measurements and near-field optical microscopy to find that the magnetic order is localized along dislocation walls and coexists with ferroelectric order along the walls. The magnetic signals can be switched on and off via external stress and altered by external electric fields, which demonstrates that plastically deformed SrTiO3 is a quantum multiferroic. These results establish plastic deformation as a versatile knob for the manipulation of the electronic properties of quantum materials. 

Magnetocaloric properties of TbCrO3 and TmCrO3 are reported and compared with those of the previously reported rare-earth chromites RCrO3 (R = Gd, Dy, Ho, and Er) and other perovskite-type oxides. The samples of TbCrO3 and TmCrO3 in this work were synthesized using a citrate gel combustion technique, and their magnetic properties were investigated and compared with those reported previously on RCrO3 (R = Gd, Dy, Ho, and Er). The Cr3+–Cr3+ ordering temperatures were found to strongly depend on the ionic radii of the rare-earth. By fitting the dc magnetization data with modified Curie–Weiss law including the Dzyaloshinsky–Moriya antisymmetric exchange interaction (D) and the symmetric exchange constant Je, spin canting angles (α) were obtained. In general, α was found to increase with the decreasing ionic radii of R3+ in RCrO3. The magnetocaloric properties investigated included the magnetic entropy change (−ΔS) for a given change in magnetic field (ΔH), the corresponding adiabatic temperature change (ΔTad), and their relative variations (ΔTad/ΔH) and (−ΔS/ΔH). It is observed that for RCrO3, (−ΔS) measured in the vicinity of the ordering temperature of R3+–R3+, varies almost as G2/3 where G is the de Gennes factor. Among RCrO3, GdCrO3 shows the largest value of (−ΔS/ΔH), because of its largest G factor and its magnitudes of (ΔTad/ΔH) and (−ΔS/ΔH) compare well with the reported values for the perovskites GdFeO3 and EuTiO3. These comparisons presented here provide useful information on the potential use of these materials in magneto-refrigeration technology.