Experimental Identification of Electric Dipoles Induced by Magnetic Monopoles in Tb2Ti2O7

Feng Jin, Changle Liu, Yanfen Chang, Anmin Zhang, Yimeng Wang, Weiwei Liu, Xiaoqun Wang, Young Sun, Gang Chen, Xuefeng Sun, and Qingming Zhang
Phys. Rev. Lett. 124, 087601 – Published 27 February 2020
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Abstract

The fundamental principles of electrodynamics allow an electron carrying both electric monopole (charge) and magnetic dipole (spin) but prohibit its magnetic counterpart. Recently, it was predicted that the magnetic “monopoles” carrying emergent magnetic charges in spin ice systems can induce electric dipoles. The inspiring prediction offers a novel way to study magnetic monopole excitations and magnetoelectric coupling. However, no clear example has been identified up to now. Here, we report the experimental evidence for electric dipoles induced by magnetic monopoles in spin frustrated Tb2Ti2O7. The magnetic field applied to pyrochlore Tb2Ti2O7 along the [111] direction, brings out a “3-in-1-out” magnetic monopole configuration, and then induces a subtle structural phase transition at Hc2.3T. The transition is made evident by the nonlinear phonon splitting under magnetic fields and the anomalous crystal-field excitations of Tb3+ ions. The observations consistently point to the displacement of the oxygen O anions along the [111] axis which gives rise to the formation of electric dipoles. The finding demonstrates that the scenario of magnetic monopole having both magnetic charge and electric dipole is realized in Tb2Ti2O7 and sheds light into the coupling between electricity and magnetism of magnetic monopoles in spin frustrated systems.

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  • Received 29 July 2019
  • Accepted 7 February 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.087601

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Feng Jin1,2, Changle Liu3, Yanfen Chang1, Anmin Zhang4, Yimeng Wang1,2, Weiwei Liu1,2, Xiaoqun Wang5, Young Sun1, Gang Chen6,3, Xuefeng Sun7, and Qingming Zhang4,1,*

  • 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 2Department of Physics, Renmin University of China, Beijing 100872, China
  • 3State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
  • 4School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
  • 5Key Laboratory of Artificial Structures and Quantum Control of MOE, Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
  • 6Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China
  • 7Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China

  • *qmzhang@ruc.edu.cn

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Issue

Vol. 124, Iss. 8 — 28 February 2020

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