FY2019 Annual Report

Electronic and Quantum Magnetism Unit
Associate Professor Yejun Feng

Abstract

This is the third year of the Electronic and Quantum Magnetism Unit at OIST. 

1. Staff & Students

  • Anjana Krishnadas, Graduate Student
  • Dr. Semyon Chervinskii, Postdoc Researcher
  • Dr. Oleksandr Smorodin, Postdoc Researcher
  • Dr. Yajian Hu, Postdoc Researcher
  • Dr. Volodymyr Monarkha, Technical Staff
  • Scott Cooper, Technical Staff
  • Yukiko Murabayashi, Administrative Assistant
  • Magarita Dronova, Intern
  • Ekaterina Toshcheva, Intern
  • Jaime Rivera, Intern 
  • Zhilin Liang, Intern
  • Celia Gonzalez, Intern
  • Houshu Hiyane, Intern
  • Tomoyuki Murata,Visiting research student from Univ. of The Ryukyus
  • Dr. Xiang Li, Visiting Postdoc from Caltech
  • Prof. Yoshitomo Karaki, Visiting Researcher, from Univ. of The Ryukyus

2. Collaborations

2.1 Synchrotron x-ray magnetic diffraction under high pressure

  • We use the resonant x-ray magnetic diffraction to study the all-in-all-out antiferromagnetic order in Sm2Ir2O7 and Eu2Ir2O7, under continous pressure tuning to a quantum critical point. 
  • Collaborators:
    • Dr. Yishu Wang, Institute for Quantum Matter, Johns Hopkins University
    • Professor Thomas Rosenbaum, Caltech
    • Professor Andrew Boothroyd, University of Oxford
    • Professor Satoru Nakatsuji, University of Tokyo

2.2 Planar Hall effects in ferromagnets

  • We explore the anomalous electron velocity physics in the magnetoresistance channels with an antisymmetric functional form. 
  • Collaborators:
    • Dr. Yishu Wang, Institute for Quantum Matter, Johns Hopkins University
    • Professor Patrick Lee, MIT
    • Professor Thomas Rosenbaum, Caltech

2.3 Linear magnetoresistance in charge and spin density wave materials

  • This is a focused interest in the linear magnetoresistance in charge density wave systems at low temperature and under low magnetic field.
  • Collaborators:
    • Professor Peter Littlewood, University of Chicago
    • Professor Thomas Rosenbaum, Caltech
    • Dr. Yishu Wang, Institute for Quantum Matter, Johns Hopkins University
    • Professor Hua Chen, Colorado State University 
    • Professor Yoshichika Onuki, RIKEN
    • Professor Riki Kobayashi, University of the Ryukyus

2.4 Optical Raman scattering under high pressure and low temperature

  • We focus on magnon Raman scattering to explore magnetic quantum phase transitions in various correlated electron systems.
  • Collaborators:
    • Dr. Xiang Li, Caltech
    • Anjana Krishnadas, OIST
    • Professor David Hsieh, Caltech
    • Professor Thomas Rosenbaum, Caltech

3. Activities and Findings

 

3.1 X-ray magnetic diffraction under high pressure

Our work on Sm2Ir2O7 was prepared in a manuscript arXiv:1912.11640. 

3.2 Optical Raman scattering under high pressure

Visiting Postdoc Dr. Xiang Li has demonstrated magnon Raman scattering beyond 5 GPa at 4K at low wave numbers below 20 cm-1. 

3.3 Synchrotron-based Mossbauer effect under high pressure

OIST graduate student Anjana Krishnadas lead the effort to explore magnetism in Eu based compounds to 50 GPa and 4K using synchrotron based Mossbauer effect at Sector 3 of the Advanced Photon Source of Argonne National Laboratory. 

3.4 Single crystal growth using high temperature solution technique

Several interns and visiting research student all worked on the sample growth technique and subsequent charcterization process. 

 

4. Publications

4.1 Journals

  1. Yishu Wang, Patrick A. Lee, D. M. Silevitch, F. Gomez, S.E. Cooper, Y. Ren, J.-Q. Yan, D. Mandrus, T. F. Rosenbaum, Yejun Feng, Antisymmetric linear magnetoresistance and the planar Hall effect. Nature Communications 11, 216 (2020).
  2. Yishu Wang, T. F. Rosenbaum, Yejun Feng, X-ray magnetic diffraction under high pressure. IUCrJ 6, 507 (2019).
  3. Yejun Feng, Yishu Wang, D.M. Silevitch, J.-Q. Yan, Riki Kobayashi, Masato Hedo, Takao Nakama, Yoshichika Ōnuki, A. V. Suslov, B. Mihaila, P. B. Littlewood, T. F. Rosenbaum, Linear magnetoresistance in the low-field limit in density-wave materials. Proc. Natl. Acad. Sci. USA 116, 11201 (2019).

4.2 Books and other one-time publications

Nothing to report

4.3 Oral and Poster Presentations

Invited talks by the PI:

  1. Zhejiang Institute of Modern Physics, Zhejiang University, Continuous all-in-all-out quantum phase transitions under pressure, Hangzhou, Zhejiang, China, Nov. 26th, 2019.
  2. JPhysics-2019, International Conference & KINKEN-WAKATE 2019 Multipole Physics, Direct observation of continuous all-in-all-out quantum phase transitions under pressure, Centennial Hall, Kobe University, Kobe, Japan. Sept 19th, 2019.
  3. Department of Physics, Chinese University of Hong Kong, Symmetric and antisymmetric linear magnetoresistances, Hong Kong, Aug. 26th, 2019.
  4. Department of Physics, Colorado State University, Odd and even linear magnetoresistances at low field. Fort Collins, CO, USA, May 2nd, 2019.

Contributed talks with the PI listed:

  1. Anjana Krishnadas et al., High pressure magnetic phase of EuGa4. Young Scientist Lecture, International Conference on the Applications of the Mossbauer Effect, ICAME2019, Dalian, China, Sept. 3rd. 2019. 

5. Intellectual Property Rights and Other Specific Achievements

Nothing to report

6. Meetings and Events

Nothing to report

7. Other

Nothing to report.