[Zhou, Kai; Zhuang, Pengfei; Dai, Wei] Tsinghua Univ, Dept Phys, Beijing 100084, Peoples R China.
[Zhou, Kai; Zhuang, Pengfei; Dai, Wei] Collaborat Innovat Ctr Quantum Matter, Beijing 100084, Peoples R China.
[Zhou, Kai] Goethe Univ Frankfurt, Inst Theoret Phys, Max von Laue Str 1, D-60438 Frankfurt, Germany.
[Zhou, Kai] Frankfurt Inst Adv Studies, Ruth Moufang Str 1, D-60438 Frankfurt, Germany.
[Xu, Nu] Lawrence Berkeley Natl Lab, Div Nucl Sci, Berkeley, CA 94720 USA.