Two-Dimensional Quantum Properties of Monolayer Helium Three Adsorbed on ZYX Graphite

ZYX石墨吸附单层氦三的二维量子特性

• 批准号: 15340113
• 负责人: FUKUYAMA Hiroshi
• 金额: $ 10.62万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 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-15340113/
• 关键词: quantum fluids; strong correlation; low dimensions; Fermi fluids; nuclear magnetic resonance; frustration; superfluid; nuclear magnetism; 比熱

We investigated strong correlation effects in two-dimensional Fermion systems by measuring hear capacities and magnetization of monolayer ^3He physisorbed on ^4He preplated graphite surfaces. Four distinct regions including so far unknown new quantum fluid phases were observed as a function of areal density, which indicates a rather complicated phase diagram for this system.At low densities (Region-I), the low temperature properties can be described well by the Fermi fluid theory where the quasi-particle effective mass is enhanced by ten times of the bare mass. Upon increasing density towards that (6.9 nm^<-2>) for the 4/7 phase which is commensurate against the underlayer, the behavior of heat capacity and magnetization deviates from the Fermi fluid theory and shows anomalous spin-mass separation like tendency (Region-II). This region should be a new quantum fluid, for which we proposed a hypothesis of the 4/7 phase (Mott localized phase) doped with the zero-point vacancies (holes). With further increasing density, there appears another region where both heat capacity and magnetization do not change appreciably (Region-III). And then above 8.3 nm^<-2> the system undergoes a two-phase coexistence region (Region-IV) between the Region-III and a ferromagnetic phase. Region-III would be also a new quantum fluid with different properties from those of Region-II. It is desired to clarify whether its fluidity comes from the liquid phase promoted to the overlayer or from the 4/7 phase doped with excess particles in the near future.We verified our previous claim of the gapless quantum spin-liquid for the magnetic ground state of the 4/7 phase. Importantly, no gapped behavior was observed at temperatures down to 0.07 mK in the whole density range we studied. This is consistent with the path integral renormalization group calculation for the Hubbard model on a triangular lattice, and would be a general property of the strongly correlated fermions with frustration.

通过测量物理吸附在~4He预镀石墨表面的单层~3He的剪切容量和磁化强度，研究了二维费米子系统中的强关联效应。观察到了四个不同的区域，其中包括迄今未知的新量子流体相，这表明该系统的相图相当复杂。在低密度区(I区)，可以用费米流体理论很好地描述低温性质，其中准粒子的有效质量是裸质量的10倍。当密度增加到与底层相称的4/7相的(6.9 nm)时，热容和磁化强度的行为偏离费米流体理论，表现出反常的自旋-质量分离趋势(区域-II)。这一区域应该是一种新的量子流体，为此我们提出了4/7相(Mott定域相)掺杂零点空位(空穴)的假说。随着密度的进一步增加，出现了另一个热容和磁化强度都没有明显变化的区域(区域III)。在8.3 nm~(-2)以上，系统经历了一个介于-III区和一个铁磁相之间的两相共存区域(-IV区)。区域III也将是一种新的量子流体，具有与区域II不同的性质。需要澄清的是，它的流动性是来自于促进到覆盖层的液体，还是来自于在不久的将来掺杂过量粒子的4/7相。我们验证了我们之前关于4/7相磁性基态的无间隙量子自旋液体的说法。重要的是，在我们研究的整个密度范围内，当温度降至0.07mK时，没有观察到有间隙的行为。这与三角晶格上Hubbard模型的路径积分重整化群计算是一致的，也是受挫的强关联费米子的一般性质。

项目成果

NMR Measurements of a Possible New Quantum Phase in 2D ^3He

2D ^3He 中可能的新量子相的 NMR 测量

• 发表时间: 2005
• 期刊: Journal of Low Temperature Physics 138
• 作者: Yonehara;Atsunori;D.Tsuji;N.Nakajima et al.;H.Akisato
• 通讯作者: H.Akisato

NMR measurements of 2D ^3He adsorbed on ZYX exfoliated graphite

ZYX 膨胀石墨吸附的 2D ^3He 的 NMR 测量

• 发表时间: 2004
• 期刊: Journal of Low Temperature Physics 134
• 作者: J.Kanasaki;K.Tanimura;S.Murakawa
• 通讯作者: S.Murakawa

S.Murakawa: "NMR measurements of 2D^3He adsorbed on ZYX exfoliated graphite"Journal of Low Temperature Physics. 134. 109-114 (2004)

S.Murakawa：“ZYX 膨胀石墨上吸附的 2D^3He 的 NMR 测量”《低温物理学杂志》。

Heat capacities of the anomalous fluid phase in two-dimensional ^3He

二维 ^3He 反常流体相的热容

• 发表时间: 2005
• 期刊: Journal of Low Temperature Physics 138
• 作者: Y.Matsumoto

Effects of ^4He substitution on low temperature heat capacities of 2D ^3He adsorbed on graphite

^4He取代对石墨吸附二维^3He低温热容的影响

• 发表时间: 2005
• 期刊: Journal of Low Temperature Physics 138
• 作者: Yonehara;Atsunori;D.Tsuji
• 通讯作者: D.Tsuji