Time-and Space-Scale Dependent Properties of Spin Systems with Exchange Frustrations

具有交换挫败的自旋系统的时间和空间尺度相关特性

• 批准号: 04452039
• 负责人: ITO Atsuko
• 金额: $ 4.48万
• 依托单位: OCHANOMIZU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452039/
• 关键词: Spin-glass; Reentrant spin-glass; Cluster-glass; Low-field -dc-magnetization; Non-linear susceptibility; Mossbauer spectra; muSR; High-field magnetization process; リエントラントスピングラス; MSR; ランダム磁性体; ランダムフラストレーション系; 高磁場磁化過程; 希釈反強磁性体; ランダム磁場; 中性子散乱

We have considered that, in order to extract multiform properties of spin-glass (SG) systems, a combined application of various techniques with different time-and space-scale of observation is useful. In this project, we investigated five short-range SG systems (see below) using the following techniques : (1) low-de-field magnetization, (2) ac-susceptibility, (3) Mossbauer spectra, (4) neutron scattering, (5) muSR,and(6) magnetization process up to high-field region. The samples examined are as follows. (A) Magnetically non-diluted system : typical Ising system Fe_xMn_<1-x>TiO_3, and Heisenberg-like system Ni_xMn_<1-x>TiO_3. (B) Diluted systems : Ising systems Fe_xZn_<1-x>F_2 and Fe_xMg_<1-x>TiO_3, and Heisenberg-like system Mn_xMg_<1-x>TiO_3. The followings are summary of our results. (1) Fe_xMn_<1-x>TiO_3 : (1) Details of x-T magnetic phase diagram was decided. (2) Experimental supports for de-Almeida-Thouless theory were given. (3) We found the phenomena consistent with the consider … More ation that the spin state reached under field-cooled conditions is stable, and the spin system forms a hierarchical organization with many valley structures. (4) Below SG-freezing temperature (TSG) , fluctuations of spins remain, which is attributed to the existence of the transverse spin component (5) The reentrant transition was suggested to be a phase transition by observing the divergent behavior of non-linear susceptibility. (2) Ni_xMn_<1-x>TiO_3 : We firstly observed with experiments that the orthogonal spin components in a Heisenberg-like system with weak spin anisotropy freeze succesively at different temperatures (x=0.42,0.47) . (3) Fe_<0.26>Zn_<0.74>F_2 and Fe_<0.2>Mg_<0.8>TiO_3 : SG-freezing was shown to occur among AF-clusters which were formed at temperatures higher than 2T_<SG>. Thus, we have identified that both systems are a typical cluster glass. We infer that this mechanism is common to SG-freezing occurring in diluted systems with concentrations near below the percolation concentration. (4) Mn_xMg_<1-x>TiO_3 : The x-T magnetic phase diagram was determined on the whole. We have found that the spin system changes at x-0.57 from an AF-system showing the random-field effect to an SG-system. Less

我们认为，为了使用自旋玻璃（SG）系统的多样性，在此项目系统中使用了各种技术的组合应用。以下技术：（1）低场磁化，（2）AC-suspecttity，（4）中子ttering，（5）Musr和（6）磁化过程至高视野区域。以下。类似Senberg的系统Ni_xmn_ <1-X> tio_3（b）稀释系统：ISING Systems Fe_xzn_ <1-x> tio_3和Heisenberg类似于Heisenberg的系统MN_XMG_ <1-x> 1）Fe_xmn_ <1-x> tio_3：（1）X-T磁相图的细节被取消了与考虑的旋转状态稳定的旋转状态，并且旋转系统是层次结构的，这是一致的。具有许多山谷结构的组织。通过实验观察到，具有弱自旋各向异性冻结的Heisenberg样系统（X = 0.42,0.47）已经确定了两个系统在稀释的系统中的典型群集X-0.57的自旋系统从A EM变化为SG系统的随机景观

项目成果

H. Kawano: "Two Successive Spin Glass Transitions in Nondiluted Heisenberg-Like Spin Glass Nio.42Mn0.58TiO3." J. Phys. Soc. Jpn.62. 2575-2578 (1993)

H. Kawano：“未稀释的类海森堡自旋玻璃 Nio.42Mn0.58TiO3 中的两个连续自旋玻璃转变。”

A. Fukaya: "Spin-Flop Transition of the Diluted Antiferromagnet Mn_XMg_<1-X>TiO_3." Physica B. 201. 88-90 (1994)

A. Fukaya：“稀释反铁磁体 Mn_XMg_<1-X>TiO_3 的自旋翻转转变。”

A. Tobo: "Concentration-Temperature PhaseDiagram of the Diluted Antiferromagnet MnxMg_<1-X>TiO_3." J. Magn. Magn. Mater.140-144(in press). (1995)

A. Tobo：“稀释反铁磁体 MnxMg_<1-X>TiO_3 的浓度-温度相图。”

A. Ito: "Studies of Diluted Antiferromagnet Fe0.2Mg0.8TiO3:Percolation Concentration and Cluster-Glass." J. Phys. Soc. Jpn.64(NO.5 in press). (1995)

A. Ito：“稀释反铁磁体 Fe0.2Mg0.8TiO3 的研究：渗滤浓度和簇玻璃。”

E. Torikai: "μ^+SR Study of Ising Spin-Glass Fe0.5Mn0.5TiO3." Hyperfine Interactions. 84. 105-108 (1994)

E. Torikai：“伊辛自旋玻璃 Fe0.5Mn0.5TiO3 超精细相互作用的 μ^+SR 研究。”