High-field magnetization, M($H$), on Ni$_{5}$(TeO$_{3}$)$_{4}$X$_{2}$ (X = Br and Cl) were measured by using a pulse magnet. These compounds have a two dimensional crystal structure and a distorted kagome spin frustrated system which is builded by the Ni$^{2+}$ ions ($\textbf{S}$ = 1). The Néel transition temperatures are $T_{N} \sim$ 28 and 23 K for X = Br and Cl, respectively. When $T < T_{N}$, we observed a step-like transition at $H_{c} \sim$ 11 and 10 T for X = Br and Cl, respectively. On the other hand, at $T > T_{N}$, the field-dependent magnetization curves behaved like a monotonically increasing straight line up to 55 T. The $H_{c}$ value is close to those obtained by previous spin resonance studies in which a model of spin-flop scenario was proposed to explain the field-dependent resonance spectra. Their model predicts a further transition at around 23 T, however, our observations did not show any plateau behaviors, saturation or other anomalies up to 55 T, suggesting that the further transition possibly exists at a much higher field region.
Ferrimagnetism and anisotropic phase tunability by magnetic fields in Na$_2$Co$_2$TeO$_6$
Na $_2$ Co $_2$ TeO $_6$最近被提出是Kitaev型蜂窝磁体。为了评估它离实现Kitaev量子自旋液体有多近,我们测量了高质量单晶在沿高对称方向施加的磁场中的磁化强度和比热。小的训练场揭示了一个弱的,但规范的亚铁磁行为低于27 K,这不能解释的锯齿形反铁磁秩序单独和建议共存的Néel型序的时刻倾斜远离锯齿形链。在蜂窝状平面中的温和的领域抑制在27 K的热转变,似乎部分逆转的时刻倾斜时,垂直于锯齿形链。与此相反,平面外的字段离开过渡基本上不受影响,但促进另一个低于10 K的过渡,也可能与倾斜反转。Na $_2$ Co $_2$ TeO $_6$中的磁性是高度各向异性的并且接近于竞争相之间的临界点。
Competition between Geometrical Frustration and the Kondo Effect in CePdAl Revealed by High-Resolution Magnetization
Institute for Solid State Physics, The University of Tokyo(东京大学固体物理研究所);Nagoya Institute of Technology(名古屋工业大学);Institute for Materials Research, Tohoku University(东北大学物质材料研究所);School of Science and Engineering, Chuo University(中央理工学院);Department of Basic Science, The University of Tokyo(东京大学基础科学系);Graduate School of Science and Engineering, Univ. of Toyama(富山理工学研究院)
Anomalous temperature and field behaviors of magnetization in cubic lattice frustrated ferromagnets
本文研究了具有竞争交换作用的立方海森堡铁磁体在阻挫点附近的热力学性质,在阻挫点附近自旋波谱$E_{\mathbf{k}}\sim D k^{2}$中的系数$D$为零。在Dyson-Maleev形式主义中,发现在低温下,热涨落通过增加$D$的值来稳定铁磁性。对于不太强的挫折,这导致了一个不寻常的“凹”形状的磁化强度的温度依赖性,这是在与实验数据的铕硫属化物。通过蒙特卡罗模拟证实了磁化强度的反常温度行为。在有限温度下的磁化强度(paraprocess)的强磁场依赖性附近的挫折点。
Frustration effects on the magnetization plateau physics in a trimerized quantum spin-1/2 chain
Instituto de Física, Universidade Federal de Mato Grosso do Sul(南马托格罗索联邦大学物理研究所);Departamento de Física, Universidade Federal de Santa Maria(圣玛丽亚联邦大学物理系)
Almost Perfect Frustration in the Dimer Magnet Ba$_2$CoSi$_2$O$_6$Cl$_2$
我们测定了本工作合成的Ba $_2$ CoSi $_2$ O $_6$ Cl $_2$的晶体结构,并利用单晶研究了它的量子磁性。这种化合物应该被描述为一个二维耦合自旋1/2 XY类自旋二聚体系统。Ba $_2$ CoSi $_2$ O $_6$ Cl $_2$表现出阶梯式磁化过程,在饱和磁化强度的一半处具有平台,而与场方向无关,尽管所有Co $^{2+}$位点是等效的。这表明自旋三重态是由于二聚体间交换相互作用的几乎完美的挫折而局部化的。因此,零和1/2磁化平台状态的自旋状态几乎完全由单重态二聚体的简单乘积和单重态和三重态二聚体的交替乘积分别给出。
Dominant Kitaev Interaction and Field-induced Quantum Disordered Phase in the Cobaltate Na$_2$Co$_2$TeO$_6$
Institute for Solid State Physics, University of Tokyo(东京大学固体物理研究所);School of Physics, Southeast University(东南大学物理学院);Anhui Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences(中国科学院合肥物质科学研究院强磁场科学中心);School of Physical Science and Engineering, Beijing Jiaotong University(北京交通大学物理科学与工程学院);Center for Quantum Materials, Seoul National University(首尔大学量子材料中心);School of Physics, Georgia Institute of Technology(佐治亚理工学院物理学院);Institute of Theoretical Physics, Chinese Academy of Sciences(中国科学院理论物理研究所)
Relieving Geometrical frustration through doping in the Dy$_{1-x}$Ca$_{x}$BaCo$_{4}$O$_{7}$ Swedenborgites
用X射线衍射、磁化强度和介电测量相结合的方法研究了反铁磁Swedenborn DyBaCoPDMATHABMM O $_{7}$的几何阻挫.在系列Dy $_{1-x}$ Ca $_{x}$ BaCo $_{4}$ O $_{7}$中的系统掺杂引起几何挫折的提升,导致在$x=0.4$处从三角P31 c到正交Pbn 2 $_{1 }$对称性的结构转变。这种结构转变也可以作为温度的函数,我们所有的斜方晶体样品在高温下都表现出这种转变。与以前的报告一致,这种结构转变发生的温度与$A$位点离子的平均离子半径成线性关系。然而,CaBaCo $_{4}$ O $_{7}$具有相同数量的Co ${^{2+}}$和Co ${^{3+}}$离子,这显然违反了这种准线性关系,表明电荷有序也可以在稳定该系统中的正交畸变中发挥关键作用。利用热释磁测量方法,克服了Dy ${^{3+}}$离子产生的大顺磁背景的问题,绘制了Dy $_{1-x}$ Ca $_{x}$ BaCo $_{4}$ O $_{7}$系列的相图。
Strong fluctuations near the frustration point in cubic lattice ferromagnets with localized moments
本文研究了具有竞争交换作用的立方海森堡铁磁体在阻挫点附近的热力学性质,在阻挫点附近自旋波谱$E_{\mathbf{k}}\sim D k^{2}$中的系数$D$为零。在Dyson-Maleev形式主义中,发现在低温下,热涨落通过增加$D$的值来稳定铁磁性。对于不太强的挫折,这导致了一个不寻常的“凹”形状的磁化强度的温度依赖性,这是在与实验数据的铕硫属化物。用蒙特卡罗模拟的方法构造了相图,并与自旋波理论的结果进行了比较,发现了磁化强度和居里温度的抑制。这种效应可以用自旋波谱的非解析修正来解释,这些修正在最低阶用$\sim (T/S)^{2} k^{2}\log{k}$表示。
Metastable magnetization behavior in magnetocaloric R6Co1.67Si3 (R=Tb and Nd) compounds
在最近发现的三元硅化物R6 Co 1.67Si 3中观察到了磁场和时间诱导的台阶。在低温磁化等温线的不同环中观察到巨大的弛豫台阶。该系统中存在的巨弛豫现象表明,在一定的磁场下,存在一个达到饱和时刻的孕育时间。在该系统中观察到的测量协议敏感的磁化行为可能是由强磁结构耦合和/或磁阻挫引起的。电阻率和磁阻也反映了化合物的磁性状态。磁热效应被发现是大的温度接近磁转变温度。
Magnetization plateau and anisotropic magnetoresistance in the frustrated Kondo-lattice compound Ce3ScBi5
Northeastern University(东北大学);University of Chinese Academy of Sciences(中国科学院大学);Institute of Physics, Chinese Academy of Sciences(中国科学院物理研究所);Southern University of Science and Technology(南方科技大学);Songshan Lake Materials Laboratory(松山湖材料实验室)
Frustration-driven unconventional magnetism in the Mn$^{2+}$ ($S=\frac{5}{2}$) based two-dimensional triangular-lattice antiferromagnet Ba$_{3}$MnTa$_{2}$O$_{9}$
Emergence of partially disordered antiferromagnetism and isothermal magnetization plateau due to geometrical frustration in a metallic compound, Er2RhSi3