Presaturation phase with no dipolar order in a quantum ferro-antiferromagnet
Presaturation phase with no dipolar order in a quantum ferro-antiferromagnet
复制标题
量子铁反铁磁体中无偶极序的预饱和相
作者：
V. K. Bhartiya;K. Povarov;D. Blosser;S. Bettler;Z. Yan;S. Gvasaliya;S. Raymond;E. Ressouche;K. Beauvois;J. Xu;F. Yokaichiya;A. Zheludev
对BaCdVO(PO$_4$)$_2$单晶进行了磁化、磁热学、量热、中子和x射线衍射及非弹性中子散射测量。发现低温晶体结构的对称性比先前假设的要低。结果是一个更复杂的模型自旋哈密顿量，这是我们从自旋波色散谱的测量推断出来的。主要发现是在高磁场中，反铁磁序在$H_{c1}simeq 4.0$ T处终止后出现了一个新的自旋态，它是一个明显的热力学相，在$H_{c1}simeq 6.5$ T处有明确的相界，与完全饱和相明显分离。然而，它没有显示出传统的（偶极）磁长程秩序。我们认为它完全符合量子键向列态的期望。
Magnetization, magnetocaloric, calorimetric, neutron and X-ray diffraction and inelastic neutron scattering measurements are performed on single crystals of BaCdVO(PO$_4$)$_2$. The low-temperature crystal structure is found to be of a lower symmetry than previously assumed. The result is a more complicated model spin Hamiltonian, which we infer from measurements of the spin wave dispersion spectrum. The main finding is a novel spin state which emerges in high magnetic fields after antiferromagnetic order is terminated at $H_{c1}simeq 4.0$ T. It is a distinct thermodynamic phase with a well-defined phase boundary at $H_{c2}simeq 6.5$ T and is clearly separate from the fully saturated phase. Yet, it shows no conventional (dipolar) magnetic long range order. We argue that it is fully consistent with the expectations for a quantum bond-nematic state.