Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe3GeTe2

3/1/2023 | C. L. Chien (Johns Hopkins University)

Anomalous Nernst effect (ANE), a result of charge current driven by temperature gradient, provides a probe of the topological nature of materials due to its sensitivity to the Berry curvature near the Fermi level. Of particular interest is the ANE in topological materials because the special band topology in these materials could introduce a very large ANE.

Charge Disproportionation and Complex Magnetism in a PbMnO3Perovskite Synthesized under High Pressure

3/1/2023 | Jianshi Zhou (University of Texas-Austin)

Because of the possible crossover of Pb and 3d transition-metal (TM) redox levels, a charge transfer between Pb and TM leads to a continuous evolution from Pb2+Ti4+O3 to Pb4+Ni2+O3 in the perovskite family of PbTMO3.

Measurement of a Magnon Chemical Potential

3/1/2023 | Gregory Fiete (Northeastern University) Jianshi Zhou (University of Texas-Austin)

For a system in equilibrium, the chemical potential of particles whose numbers are not conserved (e.g. phonons, magnons) is zero. However, for a system out-of-equilibrium, such as one where a temperature gradient is applied, there are length and time scales over which the phonon and magnon numbers are approximately conserved. For these length and time scales one may define a chemical potential for the excitations.

The Synthesis Genome: Data Mining for Synthesis of New Materials

2/28/2023 | Gerbrand Ceder, UC Berkeley

Interpretable machine-learning (ML) models were developed to predict two key solid-state synthesis conditions that must be specified for any reaction: heating temperature and heating time.

Learning from Correlations: Rare-earth Nickelates Revisited

2/21/2023 | James Rondinelli (Northwestern University)

We conducted a statistical study of the correlations between local structural distortions and critical transition temperatures of the RNiO3 family of compounds (R=rare earth). We showed gaps in scientific understanding of the reported structures of these materials known to exhibit metal-insulator and magnetic transitions and explained the discrepancies with DFT calculations.

Learning Stability of AB2X6 Compounds to Guide Synthesis of Trirutile Oxides

2/21/2023 | James Rondinelli (Northwestern University), Stephen Wilson and Ram Seshadri (UCSB)

Through machine learning methods, we find that, consistent with factors determining crystallization in other structural families, geometric and bonding constraints are the most important features determining the formation of a trirutile structure.

Featureless Optimization of Material Properties for Small Data Sets in Complex Ceramics

2/21/2023 | James Rondinelli (Northwestern University)

Electronic materials that exhibit phase transitions between metastable states (e.g., metal-insulator transition materials with abrupt electrical resistivity transformations) are challenging to decode. For these materials, conventional machine learning methods display limited predictive capability due to data scarcity and the absence of features that impede model training. In this work, we developed an adaptive optimization engine that overcomes these limitations

Magnetoentropic Mapping of GaV4S8 and GaV4Se8

2/21/2023 | Stephen Wilson and Ram Seshadri (UCSB)

Here we demonstrate the utility of the magnetoentropic mapping method in combination with computational models to rapidly identify magnetic textures such as cycloids and skyrmions in uniaxial systems

From Insulator to Metal: Chemical Design of Electronic Transitions

2/17/2023 | James Rondinelli (Northwestern University)

We identified the relationship between local structural distortions, induced by chemical ordering of cations, and the interactions governing the electronic state (insulator or metal) of LaSrAlO4. The structure of this compound hosts a broad range of chemistries known to exhibit metal-to-insulator (MIT) transitions and will enable future materials design.

Evidence of a Room-temperature Quantum Spin Hall Edge State in a Higher-order Topological Insulator

2/16/2023 | Fan Zhang (University of Texas at Dallas)

Room-temperature realization of macroscopic quantum phases is one of the major pursuits in fundamental physics. A topological insulator is a material that behaves as an insulator in its interior but whose surface contains protected conducting states.

Research Highlights