First-Principles Materials Science Research Team

Principal Investigator

PI Name Ryotaro Arita
Degree D.Sci.
Title Team Leader
Brief Resume
2000D.Sci., University of Tokyo
2000Research Associate, Department of Physics, University of Tokyo
2004Postdoctoral Researcher, Max Planck Institute for Solid State Research
2006Research Scientist/Senior Research Scientist, Condensed Matter Theory Laboratory, RIKEN
2008Associate Professor, Department of Applied Physics, University of Tokyo
2011PRESTO, Japan Science and Technology Agency
2014Team Leader, First-Principles Materials Science Research Team, RIKEN Center for Emergent Matter Science (-present)
2018Professor, Department of Applied Physics, University of Tokyo (-present)

Outline

By means of first-principles methods, our team studies non-trivial electronic properties of materials which lead to new ideas/notions in condensed matter physics or those which have potential possibilities as unique functional materials. Especially, we are currently interested in strongly correlated/topological materials such as high Tc cuprates, iron-based superconductors, organic superconductors, carbon-based superconductors, 5d transition metal compounds, heavy fermions, giant Rashba systems, topological insulators, zeolites, and so on. We aim at predicting unexpected phenomena originating from many-body correlations and establishing new guiding principles for materials design. We are also interested in the development of new methods for ab initio electronic structure calculation.

Research Fields

Physics, Materials Science

Keywords

First-principles calculations
Theoretical materials design
Strongly correlated electron systems

Results

Ab initio prediction of magnetic structures

In a magnetic material, some of the atoms in a crystal carry magnetic moments, which align themselves with their neighbors in very specific formations. The smallest building block of a magnetic material -the magnetic structure- fundamentally determines the properties of a magnet. Yet the prediction is highly nontrivial due to the many degrees of freedom in the system. We formulated a scheme to predict the magnetic structure from first principles by combining the cluster multipole method and spin density functional theory, in which we start with a sophisticated list of possible spin configurations.

The list of configurations is found in a spherical expansion analogous to how atomic orbitals are constructed, but highly adapted to the crystal symmetry. We then performed a high-throughput calculation with close to 3,000 possible magnetic structures for 131 materials and found many stable and meta-stable magnetic structures. We compared our prediction to the reference standard, which we aim to reproduce, that is, the experiment. This kind of high-throughput benchmark calculation showed that our approach can significantly narrow down the possible properties of a material.

With this scheme, the exploration of magnetic materials is pushed to enter a new paradigm of material design that lives up to the era of big data.

Scheme for magnetic structure prediction.

 

Quantum crystal structure in the 250-kelvin superconducting lanthanum hydride

Condensed-matter physicists have devoted enormous efforts to finding a room-temperature superconductor. Recently, it has been reported that LaH10 with a hydrogen cage enclosing the lanthanum atoms is formed at pressures higher than 130 GPa, and becomes a superconductor at a temperature between 250 and 260 K—about 40 K below room temperature. According to conventional (classical) calculation based on the Born-Oppenheimer approximation, the highly symmetric cage structure which favors superconductivity is stable only for pressures higher than 230 GPa, and it would distort at lower pressures.

We performed a calculation where atoms are treated like quantum objects, which are described with a delocalized wave function. While the energy landscape in the classical calculation is very complex with many minima, it is entirely reshaped by considering the quantum effect: There is only one minimum, which corresponds to the symmetric structure. We also performed a first-principles Eliashberg calculation and succeeded in reproducing the pressure dependence of the superconducting transition temperature.

 

Crystal structure of LaH10, together with a sketch of the complex classical energy landscape (top) and that of the reshaped quantum energy landscape having only one minimum (bottom).

 

Cluster multipole theory for functional antiferromagnets

Recently, functional antiferromagnets are attracting an increasing amount of attention. In contrast with ferromagnetic devices, those using antiferromagnets have several advantages: They are robust against magnetic field perturbations, which is good for data retention. Since they do not have strong stray fields, one can integrate high-density memory. The energy scale of antiferromagnets is usually higher than that of ferromagnets, which is convenient for ultrafast data processing.

Motivated by the discovery of an extremely large anomalous Hall effect (AHE), anomalous Nernst effect (ANE), and magneto-optical Kerr effect (MOKE) in Mn3X (X=Sn, Ge), we introduced a new order parameter, which we call cluster multipole (CMP) moment, and showed that CMP characterizes AHE/ANE/MOKE in antiferromagnets with general spin configurations. We also found that CMP is useful for constructing database for magnetic structure and designing new functional antiferromagnets.

 

Cluster octupole in Mn3X (X=Sn, Ge), which induces a large anomalous Hall effect, anomalous Nernst effect and magneto-optical Kerr effect.

Members

Ryotaro Arita

Team Leader arita[at]riken.jp R

Shiro Sakai

Senior Research Scientist

Yusuke Nomura

Research Scientist

Motoharu Kitatani

Special Postdoctoral Researcher

Hitoshi Mori

Postdoctoral Researcher

Publications

  1. M.-T. Huebsch, T. Nomoto, M.-T. Suzuki, R. Arita,

    Benchmark for Ab Initio Prediction of Magnetic Structures Based on Cluster-Multipole Theory

    Phys. Rev. X 11, 011031 (2021)
  2. T. Nomoto, T. Koretsune, and R. Arita

    Formation Mechanism of the Helical Q Structure in Gd-Based Skyrmion Materials

    Phys. Rev. Lett. 125, 117204 (2020)
  3. J. A. Flores-Livas, L. Boeri, A. Sanna, G. Profeta, R. Arita, and M. Eremets

    A perspective on conventional high-temperature superconductors at high pressure: Methods and materials

    Phys. Rep. 856, 1 (2020)
  4. A. Sakai, S. Minami, T. Koretsune, T. S. Chen, T. Higo, Y. M. Wang, T. Nomoto, M. Hirayama, S. Miwa, D. Nishio-Hamane, F. Ishii, R. Arita, and S. Nakatsuji

    Iron-based binary ferromagnets for transverse thermoelectric conversion

    Nature 581, 53 (2020)
  5. I. Errea, F. Belli, L. Monacelli, A. Sanna, T. Koretsune, T. Tadano, R. Bianco, M. Calandra, R. Arita, F. Mauri, and J. A. Flores-Livas

    Quantum crystal structure in the 250-kelvin superconducting lanthanum hydride

    Nature 578, 66 (2020)

Articles

お問い合わせ

2-1 Hirosawa, Wako, Saitama 351-0198 Japan

E-mail:
arita[at]riken.jp

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