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

本研究的主要结果总结在两个方面：压力对真正的有机磁性晶体中的分子间相互作用的影响和低维系统中多体量子海森堡自旋的合作现象。我们发现，居里温度的第一个报告的有机铁磁体p-NPNN（对硝基苯基硝酰基氮氧化物）的流体静压力的同时测量的磁化率和热容下降。在7 kbar以下，减少量高达45%。然而，我们最近在10 kbar的高压实验中发现，随着压力的增加，有机反铁磁体的Neel温度升高，转变温度也随之升高。这些结果与压力下动力学交换作用和势能交换作用通过各种分子轨道的竞争有关。压力下晶格维数的减少也反映在分子轨道上。在高压下，有机反铁磁体的Neel温度升高，晶格维数的减少也反映在分子轨道上。在高压下，有机反铁磁体的Neel温度升高，晶格维数的减少也反映在分子轨道上 ...更多信息 用Verdazyl自由基的各种晶体衍生物对低维体系的量子统计进行了定量检验。我们测量了p-CDTV（3-（4-氯苯基-1，5-二甲基-6-硫代咪唑基））的场和温度依赖性，得到了一维量子铁磁体的自由能，以及零度极限下的热容和磁化率的临界指数，与理论结果非常一致.利用反铁磁体的倾斜弱铁磁体，估算了TOV（1，3，5-triphenyl-6-oxoverdazyl）的二维量子贝格反铁磁体中的交错磁化率.在反铁磁磁化率测量中发现了晶格维从2到3的交叉。将二维反铁磁体中交错磁化率与自旋关联长度的标度关系与本文的结果进行了比较，以明确本文所探测到的交叉效应特征。少

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, 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.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.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。