Single Crystal Growth, Crystallography, Magnetic Susceptibility, Heat Capacity, and Thermal Expansion of the Antiferromagnetic S = 1 Chain Compound CaV2O4
A. Niazi, S. L. Bud'ko, D. L. Schlagel, J. Q. Yan, T. A. Lograsso, A. Kreyssig, S. Das, S. Nandi, A. I. Goldman, A. Honecker, R. W. McCallum, M. Reehuis, O. Pie… 展开作者
A. Niazi, S. L. Bud'ko, D. L. Schlagel, J. Q. Yan, T. A. Lograsso, A. Kreyssig, S. Das, S. Nandi, A. I. Goldman, A. Honecker, R. W. McCallum, M. Reehuis, O. Pieper, B. Lake, D. C. Johnston
The compound CaV2O4 contains V^{+3} cations with spin S = 1 and has an orthorhombic structure at room temperature containing zigzag chains of V atoms running along the c-axis. We have grown single crystals of CaV2O4 and report crystallography, static magnetization, magnetic susceptibility χ, ac magnetic susceptibility, heat capacity Cp, and thermal expansion measurements in the temperature T range of 1.8-350 K on the single crystals and on polycrystalline samples. An orthorhombic to monoclinic structural distortion and a long-range antiferromagnetic (AF) transition were found at sample-dependent temperatures T_S \approx 108-145 K and T_N \approx 51-76 K, respectively. In two annealed single crystals, another transition was found at \approx 200 K. In one of the crystals, this transition is mostly due to V2O3 impurity phase that grows coherently in the crystals during annealing. However, in the other crystal the origin of this transition at 200 K is unknown. The χ(T) shows a broad maximum at \approx 300 K associated with short-range AF ordering and the anisotropy of χabove T_N is small. The anisotropic χ(T \to 0) data below T_N show that the (average) easy axis of the AF magnetic structure is the b-axis. The Cp(T) data indicate strong short-range AF ordering above T_N, consistent with the χ(T) data. We fitted our χ(T) data near room temperature by a J1-J2 S = 1 Heisenberg chain model, where J1(J2) is the (next)-nearest-neighbor exchange interaction. We find J1 \approx 230 K, and surprisingly, J2/J1 \approx 0 (or J1/J2 \approx 0). The interaction J_\perp between these S = 1 chains leading to long-range AF ordering at T_N is estimated to be J_\perp/J_1 \gtrsim 0.04.
Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy fermion LiV$_2$O$_4$ single crystals grown using a self-flux technique
Effects of hydrostatic pressure on the magnetic susceptibility of ruthenium oxide Sr3Ru2O7: Evidence for pressure-enhanced antiferromagnetic instability
We study the fidelity susceptibility of quantum antiferromagnetic Ising chain with a long-range power law interaction $1/r^α$ using the large-scale density matrix renormalization group method. We find that the critical adiabatic dimension $μ=2$ and the critical exponent of the correlation length $ν=1$ for arbitrary $α>0$, indicating all quantum phase transitions are second-order Ising transitions. In addition, we numerically determine the complete phase diagram for $0 < α\le 3$ from the data collapse of the fidelity susceptibility and show that the critical point $h_c$ changes monotonously wit…
Magnetization measurements and time-of-flight neutron powder-diffraction studies on the high-temperature (300--980 K) magnetism and crystal structure (321--1200 K) of a pulverized YCrO$_3$ single crystal have been performed. Temperature-dependent inverse magnetic susceptibility coincides with a piecewise linear function with five regimes, with which we fit a Curie-Weiss law and calculate the frustration factor $f$. The fit results indicate a formation of magnetic polarons between 300 and 540 K and a very strong magnetic frustration. By including one factor $η$ that represents the degree of spi…
We report detailed dc magnetization, linear and non-linear ac susceptibility measurements on the hole doped disordered cobaltite La$_{0.5}$Ba$_{0.5}$CoO$_3$. Our results show that the magnetically ordered state of the system consists of coexisting non-ferromagnetic phases along with percolating ferromagnetic-clusters. The percolating ferromagnetic-clusters possibly start a magnetic ordering at the Curie temperature of 201.5(5)~K. The non-ferromagnetic phases mainly consist of antiferromagnetic-clusters with size smaller than the ferromagnetic-clusters. Below Curie temperature the system exhibi…
Magnetic topological materials have attracted much attention due to the correlation between topology and magnetism. Recent studies suggest that EuCd$_2$As$_2$ is an antiferromagnetic topological material. Here by carrying out thorough magnetic, electrical and thermodynamic property measurements, we discover a long time relaxation of the magnetic susceptibility in EuCd$_2$As$_2$. The (001) in-plane magnetic susceptibility at 5 K is found to continuously increase up to $\sim$10% over the time of $\sim$14 hours. The magnetic relaxation is anisotropic and strongly depends on the temperature and th…
Anisotropic Magnetic Response in Kondo Lattice with Antiferromagnetic Order
利用连续时间量子MonteColro（CT-QMC）和动力学平均场论（DMFT）研究了近藤晶格的磁性。DMFT+CT-QMC的方法进行了扩展，以便获得在反铁磁相的各向异性磁响应。在反铁磁相的纵向和横向磁化率的数值推导。对于RKKY制度与一个小的近藤耦合，横向磁化率不降低低于转变温度，而纵向磁化率降低预期的平均场图片。然而，在RKKY相互作用和近藤效应之间的竞争区域中，纵向和横向磁化率都在转变温度以下降低。所得结果自然地解释了CeT $_2$ Al $_{10}$（$T$ =Ru，Os，Fe）族中所观察到的磁化率的温度依赖性。
We present a spin-rotation-invariant Green-function theory for the dynamic spin susceptibility in the spin-1/2 antiferromagnetic Heisenberg model on a stacked honeycomb lattice. Employing a generalized mean-field approximation for arbitrary temperatures, the thermodynamic quantities (two-spin correlation functions, internal energy, magnetic susceptibility, staggered magnetization, N'eel temperature, correlation length) and the spin-excitation spectrum are calculated by solving a coupled system of self-consistency equations for the correlation functions. The temperature dependence of the magnet…
We investigate the thermodynamic behavior of antiferromagnetic films in external magnetic fields oriented perpendicular to the staggered magnetization. Within the systematic effective Lagrangian framework we first calculate the two-point function and the dispersion relation for the two types of magnons up to one-loop order. This allows us to split the two-loop free energy density into a piece that originates from noninteracting dressed magnons, and a second piece that corresponds to the genuine magnon-magnon interaction. We then discuss the low-temperature series for various thermodynamic quan…
Ground-state and finite-temperature properties of $S=1/2$ Heisenberg ladders with a ferromagnetic leg, an antiferromagnetic leg, and antiferromagnetic rungs are studied. It is shown that a partial ferrimagnetic phase extends over a wide parameter range in the ground state. The numerical results are supported by an analytical calculation based on a mapping onto the nonlinear $σ$ model and a perturbation calculation from the strong-rung limit. It is shown that the partial ferrimagnetic state is a spontaneously magnetized Tomonaga--Luttinger liquid with incommensurate magnetic correlation, which …
Magnetism of Cu_6 Ge_6 O_{18}-x H_2 O (x = 0 ~ 6), a compound of the one-dimensional Heisenberg $S = 1/2$ model with competing antiferromagnetic interactions
我们测量了Cu $_6$ Ge $_6$ O $_{18}$ -xH $_2$ O（$x = 0 \sim 6$）的磁化率.反铁磁（AF）转变温度（$T_{\rm N}$）以上的磁化率同意与竞争AF相互作用的一维海森堡$S = 1/2$模型的磁化率。从最近邻和次最近邻AF交换相互作用之间的估计比率，自旋系统可能位于具有无隙和有隙磁激发的自旋系统之间的边界附近。$T_{\rm N}/T_{\rm max}$的值（其中$T_{\rm max}$是磁化率最大时的温度）显示出对$x$的独特依赖性。$x$依赖性可以定性地解释作为$x$的函数的相变和无序的影响考虑。
We study the magnon contribution to the gravitomagnetoelectric (gravito-ME) effect, in which the magnetization is induced by a temperature gradient, in noncentrosymmetric antiferromagnetic insulators. This phenomenon is totally different from the ME effect, because the temperature gradient is coupled to magnons but an electric field is not. We derive a general formula of the gravito-ME susceptibility in terms of magnon wave functions and find that a difference in $g$ factors of magnetic ions is crucial. We also apply our formula to a specific model. Although the obtained gravito-ME susceptibil…
NMR characterization of spin-1/2 alternating antiferromagnetic chains in the high-pressure phase of (VO)2P2O7
通过（VO）$_{2}$ P $_{2}$ O $_{7}$高压相中$^{31}$ P和$^{51}$ V核的NMR位移测量局域磁化率，证实了存在一个独特的交替反铁磁链，其零场自旋隙为34 K. $^{31}$ P核自旋-晶格弛豫速率与低于约15 K的均匀自旋磁化率成比例，这表明静态和动态自旋磁化率的温度依赖性在不远低于自旋能的温度下变得相同。
Magnetic properties of the pyrovanadate CaCoV$_2$O$_7$ have been studied by means of the bulk magnetization and neutron powder diffraction measurements. Magnetic susceptibility in the paramagnetic phase shows Curie-Weiss behavior with negative Weiss temperature $Θ\simeq -22.5$ K, indicating dominant antiferromagnetic interactions. At $T_{\rm N} = 3.44$ K, CaCoV$_2$O$_7$ shows antiferromagnetic order, accompanied by a weak net ferromagnetic moment of $\sim 0.05$~$μ_{\rm B}/{\rm Co}^{2+}$. Neutron powder diffraction confirms the formation of antiferromagnetic order below $T_{\rm N}$. It was furt…
Anisotropic susceptibility of the geometrically frustrated spin-chain compound Ca3Co2O6
Ca_3Co_2O_6是一个具有一系列迷人性质的体系，包括磁化平台和在低温下非常缓慢的动力学。这些属性是密切相关的几何挫折，这是由于一个特定的组合的功能：（i）链排列在一个三角形晶格;（ii）有一个大的单轴各向异性;（iii）链内和链间耦合分别是铁磁性和反铁磁性。因此，单轴各向异性的Ca 3Co 2 O 6的物理性质的分析是一个至关重要的问题。然而，事实证明，迄今为止还没有对这种磁各向异性进行精确的研究。直接记录在单晶体上的磁化率数据的基础上，本研究报告的定量信息的各向异性的Ca 3Co 2 O 6。
The ground state of $λ$-(BEDT-TTF)$_2$GaCl$_4$, which has the same structure as the organic superconductor $λ$-(BETS)$_2$GaCl$_4$, was investigated by magnetic susceptibility and $^{13}$C NMR measurements. The temperature dependence of the magnetic susceptibility revealed an antiferromagnetic (AF) correlation with $J/k_{\rm B} \simeq$ 98 K. NMR spectrum splitting and the divergence of $1/T_1$ were observed at approximately 13 K, which is associated with the AF transition. We found that the AF structure is commensurate according to discrete NMR peak splitting, suggesting that the ground state o…
Neutron diffraction and magnetic susceptibility studies of orthorhombic single crystal {\Ksub} confirm the three dimensional (3D) C-type antiferromagnetic (AFM) ordering of the Mn$^{2+}$ moments at $T_{\rm N}=305 \pm 3$ K which is slightly higher than that of the parent SrMnSb$_2$ with $T_{\rm N}=297 \pm 3$ K. Susceptibility measurements of the K-doped and parent crystals above $T_{\rm N}$ are characteristic of 2D AFM systems. This is consistent with high temperature neutron diffraction of the parent compound that display persisting 2D AFM correlations well above $T_{\rm N}$ to at least $\sim …
We present a spin-rotation-invariant Green-function theory for the dynamic spin susceptibility in the spin-1/2 antiferromagnetic t-J Heisenberg model on the honeycomb lattice. Employing a generalized mean-field approximation for arbitrary temperatures and hole dopings, the electronic spectrum of excitations, the spin-excitation spectrum and thermodynamic quantities (two-spin correlation functions, staggered magnetization, magnetic susceptibility, correlation length) are calculated by solving a coupled system of self-consistency equations for the correlation functions. The temperature and dopin…
Here we investigate the thermodynamic and electronic properties of Eu$_{11}$InSb$_9$ single crystals. Electrical transport data show that Eu$_{11}$InSb$_9$ has a semiconducting ground state with a relatively narrow band gap of $320$~meV. Magnetic susceptibility data reveal antiferromagnetic order at low temperatures, whereas ferromagnetic interactions dominate at high temperature. Specific heat, magnetic susceptibility, and electrical resistivity measurements reveal three phase transitions at $T_{N1}=9.3$~K, $T_{N2} =8.3$~K, and $T_{N3} =4.3$~K. Unlike Eu$_{5}$In$_{2}$Sb$_6$, a related europiu…
We measured the temperature dependence of the magnetic susceptibility and specific heat and the magnetic-field dependence of the magnetization of CuInVO$_5$. An antiferromagnetically ordered state appears below $T_{\rm N} = 2.7$ K. We observed a $\frac{1}{2}$ quantum magnetization plateau above 30 T at 1.3 K. We show that the spin system consists of antiferromagnetic spin-$\frac{1}{2}$ tetramers with $J_1 = 240 \pm 20$ and $J_2 = -142 \pm 10$ K for the intratetramer interactions.
Exploration of low temperature phase transitions associated with quantum critical point is one of the most mystifying fields of research which is under intensive focus in recent times. In this work, through comprehensive experimental evidences, we report the possibility of achieving quantum criticality in the neighborhood of a magnetic field-tuned tricritical point separating paramagnetic, antiferromagnetic and metamagnetic phases in a magnetic insulator, DyVO4. Magnetic susceptibility and heat capacity indicate to the presence of a long-range second order antiferromagnetic transition at TN ~ …
Antiferromagnetic transition in EuFe$_2$As$_2$: A possible parent compound for superconductors
用磁化率、电阻率、热电势、霍耳和比热测量研究了三元铁砷化物EuFe $_2$ As $_2$与ThCr $_2$ Si $_2$型结构。该化合物分别在200 K和20 K左右发生两次磁性相变。发现前者伴随着磁化率的轻微下降（减去Curie-Weiss顺磁贡献后），电阻率的快速下降，热电势的大幅跳跃和比热随温度降低而出现的尖峰，所有这些都指向自旋密度波状的反铁磁转变。后者被认为与Eu $^{2+}$矩的A型反铁磁有序有关。通过与BaFe $_2$ As $_2$和SrFe $_2$ As $_2$的物理性质比较，我们预期通过适当的掺杂可以在EuFe $_2$ As $_2$中诱导出超导电性。
