Phonon-assisted crossover from a nonmagnetic Peierls insulator to a magnetic Stoner metal.
We report a unique temperature-induced insulator-metal transition in MnB4 that is accompanied by a simultaneous magnetostructural change from a nonmagnetic monoclinic mP20 phase to a magnetic orthorhombic oP10 phase. Such a concurring magnetostructural and insulator-metal transformation is a manifestation of a strong competition between Peierls and Stoner mechanisms that governs a crossover from an electron-pairing to an electron-localization scenario in this system. Therefore, the phase stability of MnB4 is controlled by a subtle interplay among the Peierls mechanism, Stoner mechanism, and phonon free energy. Our findings not only resolve the longstanding magnetostructural puzzle of MnB4 but also provide a realistic system for the Peierls-Hubbard model.
College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306, China.
Yongcheng
Y
Liang
College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306, China and State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
Xun
X
Yuan
Materials Genome Institute and Department of Physics, Shanghai University, Shanghai 200444, China.
Yanfeng
Y
Gao
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China and Materials Genome Institute and Department of Physics, Shanghai University, Shanghai 200444, China.
Wenqing
W
Zhang
Materials Genome Institute and Department of Physics, Shanghai University, Shanghai 200444, China and Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260, USA.
Peihong
P
Zhang