Polycrystalline Ba4NbIr3O12 has recently been shown to be a promising spin liquid candidate. We report an easy and reliable method to grow millimeter-sized single crystals of this trimer based spin liquid candidate material with the actual stoichiometry of Ba4Nb0.8Ir3.2O12. The growth of large crystals is achieved using BaCl2 as flux. The crystals show hexagonal plate-like habit with edges up to 3 mm in length. The structure is confirmed by single crystal X-ray diffraction and is found to be the same as of previously reported phase Ba12Nb2.4Ir9.6O36 [Ba4Nb0.8Ir3.2O12], indeed with a mixed occupancy of Nb/Ir at 3a site. The magnetic and calorimetric study on the individual single crystals confirms the possibility of a spin liquid state consistent with a recent report on a polycrystalline sample
Phonon and crystal field excitations in geometrically frustrated rare earth titanates
本文研究了几种稀土钛酸盐高温超导体的声子和晶场激发。对Gd 2 Ti 2 O 7、Tb 2 Ti 2 O 7、Dy 2 Ti 2 O 7和Ho 2 Ti 2 O 7单晶的磁性测量用于表征，而拉曼光谱和太赫兹时域光谱用于探测材料的激发。晶格激发被发现是类似的化合物在整个温度范围内的调查（295-4 K）。由此产生的全声子表征的R2 Ti 2 O 7烧绿石结构，然后用于识别在材料中观察到的晶体场激发。首次在Tb_2Ti_2O_7晶体中观察到了多种晶场激发，其中包括所有已报道的晶场激发。然而，额外的晶场激发的存在下，表明存在两个不等价的Tb 3+网站在低温结构。此外，在约13 cm-1的晶体场水平被发现是拉曼和偶极活性，表明在系统中的反转对称性破坏，从而破坏其目前的对称性解释。此外，还发现了Tb 2 Ti 2 O 7中存在明显的晶体场-声子耦合的证据.这些发现要求仔细重新评估Tb 2 Ti 2 O 7的低温结构，这可能有助于提高其理论认识。
The triangular lattice compound TlYbS$_2$ was prepared as large single crystals via a molten flux growth technique using sodium chloride. Anisotropic magnetic susceptibility measurements down to 0.4 K indicate a complete absence of long-range magnetic order. Despite this lack of long-range order, short-range antiferromagnetic interactions are evidenced through broad transitions, suggesting frustrated behavior. Variable magnetic field measurements reveal metamagnetic behavior at temperatures less than 2 K. Complex low temperature field-tunable magnetic behavior, in addition to no observable lon…
Single crystals of a new silver and-cobalt based vanadate AgCo2V3O10 were grown from a melted mixture. The crystal structure determination reveals that this new vanadate crystallizes in triclinic system with space group P-1. The structure of the titled compound is constructed from CoO6octahedra and VO4 tetrahedra sharing edges and vertices leading to an open three-dimensional framework delimiting tunnels along [001], where the Ag cations are located. The bands observed in Raman spectrum were assigned to corresponding vibrations of the VO4 groups. DC and AC magnetization (susceptibility) measur…
There are three kinds of solid states of matter that can exist in physical space: quasicrystalline (quasiperiodic), crystalline (periodic) and amorphous (aperiodic). Herein, we consider the degree of orientational order that develops upon the formation of a solid state to be characterized by the application of quaternion numbers. The formation of icosahedral quasicrystalline solids is considered alongside the development of bulk superfluidity, characterized by a complex order parameter, that occurs by spontaneous symmetry breaking in three-dimensions. Crystalline solid states are viewed as hig…
A triangular lattice selenide series of rare earth (RE), CsRESe2, were synthesized as large single crystals using a flux growth method. This series stabilized in either trigonal (R-3m) or hexagonal (P63/mmc) crystal systems. Physical properties of CsRESe2 were explored by magnetic susceptibility and heat capacity measurements down to 0.4 K. Antiferromagnetic interaction was observed in all magnetic compounds, while no long-range magnetic order was found, indicating the frustrated magnetism. CsDySe2 presents spin freezing at 0.7 K, revealing a spin-glass state. CsCeSe2 and CsYbSe2 present broad…
Spin liquid state in a three-dimensional pyrochlore-like frustrated magnet
Indian Institute of Technology Madras（马德拉斯理工学院）；Institute for Basic Science（基础科学研究院）；CEA（法国原子能和替代能源委员会）；CNRS（法国国家科学研究中心）；Université Paris-Saclay（巴黎萨克雷大学）；Institut Laue-Langevin（朗之万研究所）；STFC Rutherford Appleton Laboratory（STFC卢瑟福阿普尔顿实验室）；Sungkyunkwan University（成均馆大学）；Quantum Centre of Excellence for Diamond and Emergent Materials, Indian Institute of Technology Madras（马德拉斯理工学院钻石与新兴材料量子卓越中心）
Spin liquids are exotic phases of matter that often support emergent gauge fields and quasi-particle excitations. While spin liquids are commonly known for remaining disordered, their definition has been extended to include phases with broken symmetry corresponding to (partial) long-range order, such as chiral and nematic spin liquids for example. For Coulomb spin liquids, this ordering can be quantitatively understood via a Helmholtz decomposition between divergence-free and divergence-full terms. This phenomenon has been coined fragmentation, where spin degrees of freedom fragment into two c…
Spin-liquid-like spin dynamics in the frustrated antiferromagnet TbBO3
Indian Institute of Technology Madras（印度理工学院马德拉斯分校）；ETH Zürich（苏黎世联邦理工学院）；Paul Scherrer Institut（保罗谢尔研究所）；Jožef Stefan Institute（约瑟夫斯特凡研究所）；University of Ljubljana（卢布尔雅那大学）；Bennett University（贝内特大学）；Rutherford Appleton Laboratory（鲁瑟福阿普尔顿实验室）；University of Johannesburg（约翰内斯堡大学）
A geometrically frustrated (GF) magnet consists of localised magnetic moments, spins, whose orientation cannot be arranged to simultaneously minimise their interaction energies. Such materials may host novel fascinating phases of matter, such as fluid-like states called quantum spin liquids. GF magnets have, like all solid-state systems, randomly located impurities whose magnetic moments may ``freeze'' at low temperatures, making the system enter a spin-glass state. We analyse the available data for spin-glass transitions in GF materials and find a surprising trend: the glass-transition temper…
Signature of spin liquid state in a frustrated 3D antiferromagnet
Indian Institute of Technology Madras（印度马德拉斯理工学院）；ISIS Facility, Rutherford Appleton Laboratory（卢瑟福阿普尔顿实验室ISIS设施）；R. B. College (A Constituent Unit of Lalit Narayan Mithila University, Darbhanga)（R.B.学院（拉尔·纳亚南·米提拉大学达班加 constituent unit））；University of Johannesburg（约翰内斯堡大学）；Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay（莱昂·布里渊实验室，法国原子能和替代能源委员会，法国国家科学研究中心，巴黎萨克雷大学）
Two-dimensional (2D) quantum magnetism is a paradigm in strongly correlated many-body physics. The understanding of 2D quantum magnetism can be expedited by employing a controllable quantum simulator that faithfully maps 2D-spin Hamiltonians. The 2D quantum simulators can exhibit exotic phenomena such as frustrated quantum magnetism and topological order and can be used to show quantum computational advantages. Many experimental platforms are being developed, including Rydberg atoms and superconducting annealers. However, with trapped-ion systems, which showed the most advanced controllability…
Self-organized complex structures in nature, e.g. viral capsids, hierarchical biopolymers, and bacterial flagella, offer efficiency, adaptability, robustness, and multi-functionality. Can we program the self-assembly of three-dimensional (3D) complex structures with simple building blocks, and reach similar or higher level of sophistication in engineered materials? Here we present an analytic theory of tetrahedral nanoparticles (NPs) self-assembling in 3D space, where unavoidable geometrical frustration combined with competing attractive and repulsive inter-particle interactions lead to contro…
We investigate the electronic structure of Cs$_2$CuCl$_4$, a material discussed in the framework of a frustrated quantum antiferromagnet, by means of resonant inelastic x-ray scattering (RIXS) and Density Functional Theory (DFT). From the non-dispersive highly localized dd excitations, we resolve the crystal field splitting of the Cu$^{2+}$ ions in a strongly distorted tetrahedral coordination. This allows us to model the RIXS spectrum within the Crystal Field Theory (CFT), assign the dd orbital excitations and retrieve experimentally the values of the crystal field splitting parameters D$_q$,…
Spin glass behavior in frustrated quantum spin system CuAl2O4 with a possible orbital liquid state
CuAl 2 O 4是具有量子自旋的正常尖晶石氧化物，对于Cu 2+，S=1/2。这是一个相当独特的特征，CuAl 2 O 4的Cu 2+离子位于四面体位置，而不是像许多氧化物通常的八面体位置。在低温下，它表现出量子自旋玻璃的所有热力学证据。例如，多晶CuAl 2 O 4在低场直流磁化强度数据中显示出以~ 2K为中心的尖点，在交流磁化率中显示出明显的频率依赖性，而在磁化强度的时间依赖性中显示出对数弛豫行为。同时，在~2.3 K处的热容中存在峰值，该峰值随着磁场向更高温度移动。另一方面，当从40冷却到0.4K时，在高分辨率中子粉末衍射数据中没有新的超晶格峰的证据。这意味着，有没有长程磁序低至0.4 K，从而确认了自旋玻璃样基态的CuAl 2 O 4。有趣的是，尽管Cu 2+是Jahn-Teller活性离子，但也没有结构畸变的迹象。因此，我们认为CuAl_2 O_4最可能的基态是轨道液态。更令人感兴趣的是，它还表现出大的阻挫参数f = Theta_CW/Tm ~67，这是尖晶石氧化物报道的最大值之一。我们的观察表明，CuAl 2 O 4应该是一个罕见的例子，挫折量子自旋玻璃的轨道液体状态的一个很好的候选人。
The description and detection of unconventional magnetic states such as spin liquids is a recurring topic in condensed matter physics. While much of the efforts have traditionally been directed at geometrically frustrated antiferromagnets, recent studies reveal that systems featuring competing antiferromagnetic and ferromagnetic interactions are also promising candidate materials. We find that this competition leads to the notion of special temperatures, analogous to those of gases, at which the competing interactions balance, and the system is quasi-ideal. Although induced by weak perturbing …
