Does a critical line exist in a spin-glass phase?

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540413
• 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: Shibaura Institute of Technology
• Principal Investigator: NAKAMURA Tota 芝浦工業大学, 工学部, 教授 (50280871)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: スピングラス / モンテカルロシミュレーション / ベイズ推定 / 相関長 / スケーリング / 非平衡緩和解析

Outline of Final Research Achievements

Spin glasses (SG) are known as a prototype of many complex systems. The study began with a discovery of the canonical SG materials. However, the theoretical analyses have not been so successful in explaining the experiments. There are many contradictory results among which many debates have been held. Consequently, there is a possibility of a critical line, which is a main topic of this grant. We developed several new methods to overcome the difficulties in numerical simulations. We performed gigantically large simulations, collected very precise data and reached the following conclusions.
(1)The +-J Heisenberg SG model can explain the canonical SG experiment including values of critical exponents. (2) Numerical simulations with small sizes are plagued by the size crossover, which is an origin of many contradictions. (3) Critical lines are observed due to insufficient data precisions.
New methods developed in this grant will be applicable to many complex systems, and are very promising.

Free Research Field

物性理論