Topological Quantum Phenomena Research Unit

Principal Investigator

PI Name Tian Liang
Degree Ph.D.
Title Unit Leader
Brief Resume
2016Ph.D. in physics, Princeton University, USA
2016Postdoctoral associate, Stanford University, USA
2018Postdoctoral Researcher, Strong Correlation Quantum Transport Research Team, RIKEN Center for Emergent Matter Science
2021Assistant Professor, Tsinghua University, China (-present)
2021Unit Leader, Topological Quantum Phenomenon Research Unit, Cross-Divisional Materials Research Program, RIKEN Center for Emergent Matter Science (-present)


In our unit, we aim to investigate the intriguing physical properties in topological phases of matter and strongly correlated electron system, through the research based on the condensed matter experiment. First, from fundamental physics point of view, we pay attention to the nontrivial geometrical properties of the band structure, and aim to measure the novel electrical, thermal, and magnetic quantum effect on the system. In addition, from application point of view, we work on the design of high quality thermoelectric material and devices with low dissipation. In order to achieve the above mentioned goals, we will collaborate with the researchers all over the world and enhance the understanding of physics both from the fundamental and application aspects.

Research Fields



Condensed matter physics
Topological quantum matters
Berry phase physics
Thermoelectric effect
Strongly Correlated electron system


Berry curvature generation detected by Nernst responses in ferroelectric Weyl semimetal

The quest for non-magnetic Weyl semimetals with high tunability of phase has remained a demanding challenge. As the symmetry-breaking control parameter, the ferroelectric order can be steered to turn on/off the Weyl semimetals phase, adjust the band structures around the Fermi level, and enlarge/shrink the momentum separation of Weyl nodes which generate the Berry curvature as the emergent magnetic field. Here, we report the realization of a ferroelectric non-magnetic Weyl semimetal based on indium-doped Pb1−xSnxTe alloy where the underlying inversion symmetry as well as mirror symmetries are broken with the strength of ferroelectricity adjustable via tuning indium doping level and Sn/Pb ratio. The transverse thermoelectric effect, i.e., Nernst effect, both for out-of-plane and in-plane magnetic-field geometry, is exploited as a Berry-curvature-sensitive experimental probe to manifest the generation of Berry curvature via the re-distribution of Weyl nodes under magnetic fields. The results demonstrate a clean non-magnetic Weyl semimetal coupled with highly tunable ferroelectric order, providing an ideal platform for manipulating the Weyl fermions in non-magnetic system.

The left panel shows the topological phase transition in the system of In-PbSnTe. Since the spatial inversion symmetry is broken by ferroelectricity, a Weyl semimetal phase appears. The right panel shows anomalous Hall and thermoelectric Hall effect, which originates from the Berry curvature generated by the Weyl nodes.


Tian Liang Unit Leader tian.liang[at]


  1. C.-L. Zhang, T. Liang, N. Ogawa, Y. Kaneko, M. Kriener, T. Nakajima, Y. Taguchi, and Y. Tokura

    Highly tunable topological system based on PbTe-SnTe binary alloy

    Phys. Rev. Mater. 4, 091201 (2020)
  2. J. J. He, T. Liang, Y. Tanaka, and N. Nagaosa

    Platform of chiral Majorana edge modes and its quantum transport phenomena

    Commun. Phys. 2, 149 (2019)
  3. K. Yasuda, H. Yasuda, T. Liang, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, N. Nagaosa, M. Kawasaki, and Y. Tokura

    Nonreciprocal charge transport at topological insulator/superconductor interface

    Nat. Commun. 10, 2734 (2019)


Room C337, Department of Physics, Tsinghua University, Beijing, China 100084 Japan

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