Study on Mechanism of Interaction in Organic Radical Ferromagnets

有机自由基铁磁体相互作用机理研究

• 批准号: 07454085
• 负责人: TAKEDA Kazuyoshi
• 金额: $ 4.86万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454085/
• 关键词: Orgnic ferromagnets; Pressure effects; Low-dimensional magnetic system; Many-body quantum statistics; Intermolecular interaction; Heisenberg model; Magnetic properties; Susceptibility; 有機磁性体; 低次元格子磁性体; 有機ラジカル; ハイゼンベルグスピン; 量子統計理論

The main results of the present research are summarized in two ways ; pressure effects on intermolecular interactions in genuine organic magnetic crystals and cooperative phenomena in many-body quantum Heisenberg spins in low-dimensional systems. We found that the Curie temperature of the first reported organic ferromagnet p-NPNN (para-nitrophenyl nitronyl nitroxide) decreases with hydrostatic pressures by the simultaneous measurements of magnetic susceptibility and heat capacity. The reduction amounts as much as 45% under 7kbar. Recent our experiments in the higher pressures up to 10kbar, however, have revealed the transition temperature turns to increase as the pressure induced enhancement of the Neel temperature of organic antiferromagnets.These results are relevant to competition between the kinetic and the potential exchange interactions via various molecular orbitals under the pressure.The reduction of the lattice dimensionality under pressure is also found to be reflected on the … More change of the magnetic heat capacity of this compound.Quantitative check of quantum statistics in low-dimensional systems is exanined using various crystalline derivatives of verdazyl radical. We measured field and temperature dependence of p-CDTV (3-(4-chlorophenyl-1,5-dimethyl-6-thioxoverdazyl) and got an excellent agreement with the theoretical results for the free energy for one-dimensional quantum ferromagnet, as well as the critical indices of heat capacity and magnetic susceptibility at the limit of zero degree. The staggered susceptibility, which is a fictitious but intrinsic quantity for antiferromagnets, is estimated in a two-demensional quantum Heisen berg Heisenberg antiferromagnet of TOV (1,3,5-triphenyl-6-oxoverdazyl), by making use of the canted weak ferromagnets in this system. The latticedimensional crossover from two to three in antiferromagnetic susceptibility measurements has been revealed. The scaling relation between the staggered susceptibility and the spin correlation length in two-dimensional antiferro-magnet is compared with the present result to make clear the crossover effect feature detected here. Less

本研究的主要结果以两种方式总结了。在低维系统中，多体量子海森堡旋转中真正有机磁性晶体和合作现象中分子间相互作用的压力影响。我们发现，第一个报道的有机铁磁性P-NPNN的居里温度（二硝基苯基硝基硝基氧化物）通过同时测量磁敏感性和热容量的同时测量而随着静水压力而降低。在7kbar以下的减少量高达45％。然而，我们最近在高达10KbAR的较高压力中进行的实验表明，随着压力诱导的有机抗抗铁磁铁的NEEL温度的升高，过渡温度的变化升高，结果与这些结果在压力下的磁力降低相关的效果相关。复合性检查低维系统中的量子统计量使用Verdazyl自由基的各种晶体衍生物生效。我们测量了P-CDTV（3-（4-氯苯基-1,5-二甲基-6-二甲基二唑）的场和温度依赖性，并与一维量子量子的自由能的理论结果非常吻合，并具有较大的量子量的高度量子和磁性的量子。 antiferromagnets, is estimated in a two-demensional quantum Heisenberg Heisenberg antiferromagnet of TOV (1,3,5-triphenyl-6-oxoverdazyl), by making use of the canted weak ferromagnets in this system. The latticedimensional crossover from two to three in antiferromagnetic susceptibility measurements has been revealed. The scaling relationship between the比较了二维抗磁铁中的交错敏感性和自旋相关长度与目前的结果进行了比较，以清楚此处检测到的交叉效应

项目成果

S.Takagi,K.Takeda et al.: "Magnetic Susceptibility of a Spin 1/2 Heisenberg Antiferromagnetic Chain : 〔3,3′-Dimethyl-2,2′-Thiazolinocyanine〕-TCNQ" J.Phys.Soc.Jpn. 65. 1934-1937 (1996)

S. Takagi、K. Takeda 等人：“自旋 1/2 海森堡反铁磁链的磁化率：[3,3-二甲基-2,2-噻唑啉氰]-TCNQ”J.Phys.Soc.Jpn。 65. 1934-1937 (1996)

K.Takeda, K.Konishi, M.Hitaka, K.Nedachi and M.Mukai: "Prototype one-dimensional Heisenberg ferro-magnetic interaction in the organic radical crystal" J.Magn.Magn.Mater. Vol.140-144. 1635-1636 (1995)

K.Takeda、K.Konishi、M.Hitaka、K.Nedachi 和 M.Mukai：“有机基晶体中一维海森堡铁磁相互作用的原型”J.Magn.Magn.Mater。

K.Takeda, K.Konishi, K.Nedachi and K.Mukai: "Experimental Study of Quantum Statistics for S=1/2Quasi-one-dimensional Organic Ferromagnet" Phys.Rev.Lett. Vol.74. 1673-1676 (1995)

K.Takeda、K.Konishi、K.Nedachi 和 K.Mukai：“S=1/2 准一维有机铁磁体的量子统计实验研究”Phys.Rev.Lett。

K.Mukai, K.Konishi, N.Nedachi and K.takeda: "Bulk ferro-and antiferromagnetic behavior in 1,5-dimethyl verdazyl radical crystals with similar molecular structure." J.Magn.Magn.Master. Vol.140-144. 1449-1450 (1995)

K.Mukai、K.Konishi、N.Nedachi 和 K.takeda：“具有相似分子结构的 1,5-二甲基 verdazyl 自由基晶体中的体铁磁和反铁磁行为。”

Kazuyoshi Takeda: "Experimental Check of Heisenberg Chain Quantuw Statistics for a Ferromagnetic Organic Radical Crystal" J. Phys. Soc. Jpn. 64. 2343-2346 (1995)

Kazuyoshi Takeda：“铁磁有机自由基晶体的海森堡链量子统计的实验检查”J. Phys。