New type of ordered phases due to effective longrange interaction of lattice deformation

2016 Fiscal Year Final Research Report

• Project/Area Number: 25400391
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Mathematical physics/Fundamental condensed matter physics
• Research Institution: The University of Tokyo
• Principal Investigator: Miyashita Seiji 東京大学, 大学院理学系研究科(理学部), 教授 (10143372)
• Research Collaborator: ENACHESCU Cristian Faculty of Physics-“Alexandru Ioan Cuza"University, Associate professor ; ARNE RIKVOLD Per Florida State University, Department of Physics, Distinguished Research Professor and the James G. Skofronick Professor of Physics. ; BOUKHEDDADEN Kamel University of Versailles Saint-Quentin, Professor ; COLLET Eric University of Rennesl, Professor
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: 相転移 / スピンクロスオーバー系 / 弾性相互作用 / 長距離力 / 準安定状態

Outline of Final Research Achievements

We have studied the effect of elastic interaction on the phase transitions of spin-crossover systems. The effect causes an effective long-range interaction among the spin states. In particular, when the short-range interaction is antiferromagnetic, we discovered a peculiar phase structure due to the metastable state of ferromagnetic phase. We also studied cases of frustrated lattices, e.g., the antiferromagnets on the triangular lattice. There we found new types of order states, and also an anomalous size-dependence of metastable state. Moreover, we studied the dynamics after photo-irradiation which converts the low-spin state to high-spin state, and found the so-called elastic expansion which appears before the expansion due to the thermal effect. We have also studied several related topics on the cooperative phenomena.

Free Research Field

統計力学、物性基礎論、磁性