Adsorption Structures and Competition of Multiple Spin Exchange Interactions in Two-dimensional Quantum Solids.

二维量子固体中多重自旋交换相互作用的吸附结构和竞争。

• 批准号: 15540330
• 负责人: MORISHITA Masashi
• 金额: $ 2.3万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540330/
• 关键词: Two-dimension System; Quantum Solid; Quantum Spin System; Multiple Spin Exchange Interaction; Adsorption Structure; Helium-3; Graphite; Thermal Conductivity

Helium-3 (^3He) solid films adsorbed on a graphite surface are considered as ideal materials of two-dimensional spin system. In the ^3He solid films, the competition of multiple spin exchange(MSE) interactions dominates the magnetic interactions and complicates the magnetism. Recently, the important roll of the corrugation of the adsorption potential, or the adsorption structures, on the MSE competition has been recognized.In this research we measured the heat capacity of the ^3He solid films in the commensurate areal density regime down to sub-mK temperature for the first time. We observed almost inversely proportional behavior, C ∝ T^α (α【approximately equal】 -1), in the wide temperature range more than two decades as in other areal density regimes. This behavior is unusual and anomalous as the heat capacity of localized spin systems in the high temperature limit, and is attributed to the strong competition of the MSE interactions. The α value is thought to be smaller as the MSE comp … More etition is stronger. The observed absolute value of the exponent α is larger in the commensurate areal density regime than in the incommensurate regime and shows the MSE competition is very strong. This observation agrees with the prediction that in the commensurate structure the corrugation of the adsorption potential suppresses spin exchanges, especially lower-order exchanges, and the MSE competition should be stronger than in incommensurate structures.The mechanisms of cooling ^3He films through substrates have not clearly understood either. We also measured the thermal conductivity between ^3He films and graphite substrates by the relaxation method. The measured thermal conductivity shows similar areal density variation with the strength of the MSE interaction. This observation indicates that the measured thermal conductivity is the thermal conductivity of the ^3He film itself, not of the interface, and the heat is transferred only by local spots between ^3He films and graphite substrates. It suggests the magnetic Kapitza mechanism between 3^He spins and magnetic impurities in graphite substrates. The preliminary measurements in magnetic fields, in which strong magnetic field dependence was observed, support this hypothesis. Less

吸附在石墨表面的氦-3（^3He）固体膜被认为是二维自旋系统的理想材料。在^3He固体薄膜中，多重自旋交换（MSE）相互作用的竞争主导了磁性相互作用，使磁性变得复杂。近年来，人们认识到吸附势或吸附结构的变化对MSE竞争的重要作用，在本研究中，我们首次测量了在低于mK温度的相称面密度范围内^3He固体薄膜的热容。我们观察到几乎成反比的行为，C <$T^α（α[近似等于] -1），在宽的温度范围超过二十年，在其他面密度制度。这一行为与定域自旋系统在高温极限下的热容一样是不寻常和反常的，并且归因于MSE相互作用的强烈竞争。α值被认为较小，因为MSE补偿 ...更多信息 etition更强。在公度面密度区观察到的指数α的绝对值比在非公度区大，说明MSE竞争很强。这一观察结果与预测一致，即在公度结构中，吸附势的波纹抑制了自旋交换，尤其是低阶交换，并且MSE竞争应该比无公度结构中更强。通过衬底冷却^3 He膜的机制也尚未清楚。我们还用弛豫法测量了^3He薄膜与石墨衬底之间的热导率。测得的热导率显示出类似的面密度变化与MSE相互作用的强度。这一观察结果表明，测得的热导率是^3He薄膜本身的热导率，而不是界面的热导率，热量仅通过^3He薄膜和石墨衬底之间的局部点传递。结果表明，3^He自旋与石墨衬底中磁性杂质之间存在磁性Kapitza机制。在磁场中的初步测量，其中观察到强烈的磁场依赖性，支持这一假设。少

项目成果

Heat transfer between ^3He film and graphite substrate

^3He薄膜与石墨基板之间的传热

• 发表时间: 2005
• 期刊: Journal of Physics and Chemistry of Solid 66
• 作者: A.Masago;S.Watanabe;K.Tagami;M.Tsukada;M.Morishita
• 通讯作者: M.Morishita

Thermal Relaxation of ^3He Solid Films Adsorbed on Graphite

石墨上吸附^3He固体薄膜的热弛豫

• 发表时间: 2005
• 期刊: Journal of Low Temperature Physics 138
• 作者: T.Watanabe;H.Yokoyama;Y.Tanaka;J.Inoue;M.Ogata;S.Takahashi;T.Yamashita;S.Takahashi;T.Yamashita;H.Imamura;T.Yamashita;S.E.Barnes;S.Kaji;T.Yamashita;T.Yamashita;S.Kaji;T.Yamashita;T.Yamashita;S.Maekawa;S.Kaji;J.Martinek;前川 禎通;T.Yamashita;T.Yamashita;T.Yamashita;S.Kaji;M.Morishita;M.Morishita
• 通讯作者: M.Morishita

Striped - honeycomb transition of domain wall structure of ^3He submonolayer solid film on graphite

石墨上^3He亚单层固体薄膜的条纹-蜂窝状转变结构

• 发表时间: 2003
• 期刊: Physica B 329-333
• 作者: M.Morishita;T.Takagi
• 通讯作者: T.Takagi

Heat Capacities of Submonolayer Solid ^3He Films on Graphite at Highly Frustrated Density Regime

石墨上亚单层固体 ^3He 薄膜在高度受抑密度状态下的热容

• 发表时间: 2005
• 期刊: Journal of Low Temperature Physics 138
• 作者: T.Watanabe;H.Yokoyama;Y.Tanaka;J.Inoue;M.Ogata;S.Takahashi;T.Yamashita;S.Takahashi;T.Yamashita;H.Imamura;T.Yamashita;S.E.Barnes;S.Kaji;T.Yamashita;T.Yamashita;S.Kaji;T.Yamashita;T.Yamashita;S.Maekawa;S.Kaji;J.Martinek;前川 禎通;T.Yamashita;T.Yamashita;T.Yamashita;S.Kaji;M.Morishita
• 通讯作者: M.Morishita

M.Morishita, T.Takagi: "Striped honeycomb transition of domain wall structure of ^3He submonolayer solid film on graphite"Physica B. 320-333. 137-139 (2003)

M.Morishita，T.Takagi：“石墨上 ^3He 亚单层固体薄膜的磁畴壁结构的条纹蜂窝过渡”Physica B. 320-333。