Spin-controlled molecular spatial configuration and related magnetic-field-induced phenomena

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04009
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: Matsuda Yasuhiro 東京大学, 物性研究所, 准教授 (10292757)
• Co-Investigator(Kenkyū-buntansha): 小林 達生 岡山大学, 自然科学研究科, 教授 (80205468)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 分子性結晶 / スピン / 構造相転移 / 磁場

Outline of Final Research Achievements

The phase diagram of solid oxygen was obtained in magnetic field-temperature plane. The α-β, β-γ phase boundaries were measured by the magneto-caloric effect and the triple point between the high-magnetic-field θ-, γー, and β-phases was also determined. The technique for the magnetostriction measurement in ultrahigh magnetic fields has been developed using the fiber Bragg grating. The quantum spin-state transition in LaCoO3 was detected as the structural phase transition by applying ultrahigh magnetic fields of up to 150 T. This technique was also applied to uncover the properties of the Kagome lattice, volborthite. The S=1/2 and S=1 spin ladder organic compounds BIP-BNO and BIP-TENO have been investigated by the magnetization process and found that the S=1 spin ladder exhibits unusual magnetization process, by contrast that the S=1/2 compound shows predictable magnetization process. These facts suggest that the strong spin-lattice coupling and its dynamics are important.

Free Research Field

固体物理

Academic Significance and Societal Importance of the Research Achievements

固体酸素の磁場ー温度相図を初めて明らかにし、スピンによる分子立体配置制御が分子性固体の性質をコントロール可能であることを明確に示した。分子性固体はその結晶の多様性から機能デバイスへの応用においても重要であり、スピンを介した磁気デバイスへの拡大においても重要な成果である。さらに、S=1のスピンラダー物質BIP-TENOでは、マイクロ秒の高速磁場掃引でのみ現れる量子状態（磁化プラトー状態）が見出された。磁歪の磁場掃引速度依存性から、スピン格子結合を介した磁場誘起の分子配置ダイナミクスがその理解に重要であると予想した。分子性結晶において非平衡状態を利用した量子状態制御の可能性を見出した。