Magnetic structure of single crystalline TmB4 has been studied by magnetization, magnetoresistivity and specific heat measurements. A complex phase diagram with different antiferromagnetic (AF) phases was observed below TN1 = 11.7 K. Besides the plateau at half-saturated magnetization (1/2 MS), also plateaus at 1/9, 1/8 and 1/7 of MS were observed as function of applied magnetic field B//c. From additional neutron scattering experiments on TmB4, we suppose that those plateaus arise from a stripe structure which appears to be coherent domain boundaries between AF ordered blocks of 7 or 9 lattice constants. The received results suggest that the frustration among the Tm3+ magnetic ions, which maps to a geometrically frustrated Shastry-Sutherland lattice lead to strong competition between AF and ferromagnetic (FM) order. Thus, stripe structures in intermediate field appear to be the best way to minimize the magnetostatic energy against other magnetic interactions between the Tm ions combined with very strong Ising anisotropy.
We report the $\mathbf{H}-T$ phase diagram of $S=1/2$ strongly frustrated anisotropic spin chain material linarite PbCuSO$_4$(OH)$_2$ in tilted magnetic fields up to 10 T and temperatures down to 0.2 K. By means of torque magnetometry we investigate the phase diagram evolution as the magnetic field undergoes rotation in $\mathbf{ba}^{\ast}$ and $\mathbf{bc}$ planes. The key finding is the robustness of the high field spin density wave-like phase, which may persist even as the external field goes orthogonal to the chain direction $\mathbf{b}$. In contrast, the intermediate collinear antiferroma…
Magnetic Phase Diagrams with Possible Field-induced Antiferroquadrupolar Order in TbB$_2$C$_2$
利用磁化强度与温度和磁场的关系,阐明了四元反铁磁体TbB $_2$ C $_2$的磁相图.值得注意的是,TbB $_2$ C $_2$中的N{ε}el温度随着磁场的增加而增加,特别是对于${<}1 1 0{>}$方向在10 T下的增加达到13.5 K。假设TbB $_2$ C $_2$中存在场诱导的反铁四极有序相,可以很好地解释磁化过程和相图。AFQ化合物在RB $_2$ C $_2$中的相图在AFQ和AFM相互作用的竞争方面被系统地理解。
In-field DC and AC magnetization measurements were carried out on a sigma-phase Fe55Re45 intermetallic compound aimed at determination of the magnetic phase diagram in the H-T plane. Field cooled, M_FC, and zero-field cooled, M_ZFC, DC magnetization curves were measured in the magnetic field, H, up to 1200 Oe. AC magnetic susceptibility measurements were carried out at a constant frequency of 1465 Hz under DC fields up to H=500 Oe. The obtained results provide evidences for re-entrant magnetism in the investigated sample. The magnetic phase diagrams in the H-T plane have been outlined based on…
Frustrated one-dimensional quantum spin systems are known to exhibit a variety of quantum ground states due to the effects of quantum fluctuations and frustrations. In a spin-1/2 kagome-strip chain, which is one of the frustrated one-dimensional spin systems, many quantum phases have been found. However, the magnetic phase diagrams of the kagome-strip chain under magnetic field have not been fully understood. We construct magnetic phase diagrams at 0, 1/5, 3/10, 1/3, 2/5, 7/15, 3/5, and 4/5 magnetization ratio in the kagome-strip chain and investigate magnetic properties in each phase using th…
Magnetic Properties and Phase Diagram of Li-doped La(2)CuO(4): Common Magnetic Response of Hole-doped CuO2 Planes
虽然La(2)Cu(1-x)Li(x)O(4)[Li-LCO]在许多方面不同于La(2-x)Sr(x)CuO(4)[Sr-LCO](例如,不存在金属输运、高Tc超导性和无公度反铁磁关联),已知某些磁性非常相似。本文建立了Li-LCO(0 <= x <= 0.07)的详细体磁相图,发现它与轻掺杂Sr-LCO的体磁相图几乎相同,从而将该相图的普遍性推广到空穴掺杂但非超导的铜酸盐。
A single-crystal sample of the frustrated quasi one-dimensional quantum magnet Cs$_{2}$Cu$_{2}$Mo$_{3}$O$_{12}$ is investigated by magnetic and thermodynamic measurements.A combination of specific heat and magnetic torque measurements maps out the entire $H$-$T$ phase diagram for three orientations.Remarkably, a new phase emerges below the saturation field, irrespective of the crystal orientation. It is suggested that the presaturation phase represents spin-nematic order or other multi-magnon condensate. The phase diagrams within the long-range ordered dome are qualitatively different for each…
Substitution effects on the temperature vs. magnetic-field phase diagrams of the quasi-1D effective Ising spin-1/2 chain system BaCo$_2$V$_2$O$_8$
BaCo $_2$ V $_2$ O $_8$是一个一维反铁磁自旋1/2链系统,具有明显的伊辛磁交换各向异性。由于有限的链间相互作用,长程反铁磁有序发展低于$T_{\rm N} \simeq 5.5$ K,这是伴随着结构畸变,以解除磁挫折效应。相应的温度$vs. $磁场相图相对于磁场方向是高度各向异性的,并且各种细节仍在生动的讨论中。在这里,我们报告的影响,几个替代的磁性和相图的BaCo $_2$ V $_2$ O $_8$。我们调查的替代系列Ba $_{\text{1-x}}$ Sr $_{\text{x}}$ Co $_{\text{2}}$ V $_{\text{2}}$ O $_{\text{8}}$在整个范围$0\le x \le 1$以及少量的其他磁性过渡金属或非磁性镁的磁性Co $^{2+}$的部分替代的影响。在所有情况下,相图获得单晶的磁化数据和/或高分辨率的热膨胀和磁致伸缩的研究。
Heat Capacity and Magnetic Phase Diagram of the Low-Dimensional Antiferromagnet Y$_2$BaCuO$_5$
本文对低维磁性系统Y-$_2$-BaCuO-$_5$多晶样品的比热进行了研究。施加高达14 T的磁场,并允许提取($T$,$H$)相图。低于$μ_0H^*\simeq2$ T时,与三维反铁磁长程有序有关的内尔温度是恒定的,等于$T_N=15.6$ K。在$H^*$之上,$T_N$随$H$线性增加,并且在$T_N$处的场诱导熵增加与在$T_X\simeq20$ K处的等吸光点的存在有关,在该等吸光点处所有比热曲线交叉。本文比较了Y-$_2$-BaCuO-$_5$和BaNi $_{2}$ V $_{2}$ O $_{8}$、Sr-$_2$-CuO-$_2$-Cl-$_2$和Pr-$_2$-CuO-$_4$等准二维磁系的相图。提出了一种有效的场致磁各向异性来解释这些相图。
The spin-1 Ising model with bilinear and quadrupolar short-range interactions under magnetic field is investigated within the two-particle cluster approximation. It is shown that for those values of the quadrupolar interaction when at zero magnetic field the system undergoes a temperature phase transition between quadrupolar and paramagnetic phases, a triple point may exist in the temperature vs magnetic field phase diagrams, necessarily along with a critical point. It is also shown that the critical points in the temperature vs magnetic field phase diagrams of the investigated model can be of…
Magnetic phase diagram of antiferroquadrupole ordering in HoB2C2
通过测量$x$-$y$基面和[001]主轴上的弹性常数$C_{11}$、$C_{44}$和$C_{66}$,研究了四元HoB $_2$ C $_2$的反铁四极(AFQ)有序磁相图.筑波磁实验室的混合磁体(GAMA)用于高达30 T的强场测量。沿[001]主轴在26.3 T以上时不再观察到AFQ相位,而沿[110]主轴施加的磁场中的临界磁场相对较小,为3.9 T。$O_{xy}$和/或$O_2^2$的四极位间相互作用与HoB $_2$ C $_2$中AFQ相的磁相图中的各向异性一致。
Frustrated spin ladders show magnetization plateaux depending on the rung-exchange interaction and frustration defined by the ratio of first and second neighbor exchange interactions in each chain. This paper is the first report on its magnetic phase diagram. Using the variational matrix-product state method, we accurately determine phase boundaries. Several kinds of magnetization plateaux are induced by the frustration and the strong correlation among quasi-particles on a lattice. The appropriate description of quasi-particles and their relevant interactions are changed by a magnetic field. W…
Magnetic phase diagram of the antiferromagnetic pyrochlore Gd2Ti2O7
Gd 2 Ti 2 O 7是烧绿石晶格上的高度受抑的反铁磁体,除了海森堡交换之外,自旋还通过偶极-偶极力相互作用。本文报道了在三个不同方向的外加磁场作用下对Gd_2 Ti_2 O_7单晶进行的低温比热测量。测量结果显示,强烈的各向异性行为的Gd 2 Ti 2 O 7在磁场中,尽管明显缺乏一个显着的单离子各向异性的Gd 3+。给出了H//[111]、H//[110]和H//[112]的H-T相图。结果表明,进一步的理论工作超出了一个简单的平均场模型是必要的。
Magnetic phase diagram of TbMn$_{1-x}$Fe$_x$O$_3$ $(0 \leq x \leq 1)$ substitutional solid solution
本文给出了TbMn_(1-x)Fe_xO_3替代固溶体在0 <= x <= 1的整个浓度范围内的磁相图。我们已经发现,在浓度范围0 <= x < 0.3的主要磁性离子是锰,而铁离子不产生独立的磁性结构,但强烈影响母体化合物的磁性,通过减少过渡到磁有序状态和过渡到摆线相。在0.3 < x <= 1的浓度范围内,磁性由Fe亚晶格驱动。锰离子在2K以上的温度下仍然不处于长程磁有序状态,而是稳定了Fe亚晶格的四种不同的磁结构。Tb亚晶格的磁有序只观察到母体化合物TbMnO 3和TbFeO 3和掺杂水平低于0.1,或超过0.9。
Various auxiliary-particle approaches to treat electron correlations in many-electron models are analyzed. Applications to copper-oxide layered systems are discussed. The ground-state magnetic phase diagrams are considered within the Hubbard and $s$-$d$ exchange (Kondo) models for square and simple cubic lattices vs. band filling and interaction parameter. A generalized Hartree-Fock approximation is employed to treat commensurate ferro-, antiferromagnetic, and incommensurate (spiral) magnetic phases, and also magnetic phase separation. The correlations are taken into account within the Hubbard…
Recent theoretical studies have suggested that Kitaev physics and such effects as formation of a mysterious spin-liquid state can be expected not only in RuCl3 and iridates, but also in conventional $3d$ transition metal compounds. Using DC and AC magnetometry, thermodynamic and $^{23}$Na nuclear magnetic resonance measurements (NMR) we studied such a candidate material Na3Co2SbO6. A full phase diagram of Na3Co2SbO6 in a wide range of magnetic fields and temperatures is presented. The results demonstrate transformation of the antiferromagnetic structure under the external magnetic field, gradu…
We report formation of magnetic textures in the ferromagnetic (FM) phase of La$_{1-x}$Sr$_x$MnO$_3$ for $x =$ 0.125; these textures are magnetic bubbles, magnetic stripe domains, and forced FM states. In situ Lorentz microscopy (LM) observations show that magnetic bubbles exist in the FM insulating phase accompanying the formation of the charge$/$orbital ordering (CO$/$OO). Furthermore, stable magnetic bubbles still exist in an intermediate temperature region between the CO$/$OO ($T_{CO} =$ 155 K) and FM ($T_c =$ 190 K) transition temperatures. These magnetic bubbles are believed to originate …
Recently, Yb-based triangular lattice antiferromagnets have garnered significant interest as possible quantum spin liquid candidates. One example is YbMgGaO4, which showed many promising spin liquid features, but also possesses a high degree of disorder owing to site-mixing between the non-magnetic cations. To further elucidate the role of chemical disorder and to explore the phase diagram of these materials in applied field, we present neutron scattering and sensitive magnetometry measurements of the closely related compound, YbZnGaO4. Our results suggest a difference in magnetic anisotropy b…
The tetragonal intermetallic compound EuAl$_{4}$ hosts an exciting variety of low temperature phases. In addition to a charge density wave below 140 K, four ordered magnetic phases are observed below 15.4 K. Recently, a skyrmion phase was proposed based on Hall effect measurements under a $c$-axis magnetic field. We present a detailed investigation of the phase transitions in EuAl$_{4}$ under $c$-axis magnetic field. Our dilatometry, heat capacity, DC magnetometry, AC magnetic susceptibility, and resonant ultrasound spectroscopy measurements reveal three magnetic phase transitions not previous…