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arXiv 1706.06299cond-mat.str-elcond-mat.stat-mech
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阻挫自旋1金刚石反铁磁体中的量子自旋液体

Quantum spin liquids in frustrated spin-1 diamond antiferromagnets

Finn Lasse Buessen, Max Hering, Johannes Reuther, Simon Trebst

摘要:

受最近合成的自旋-1A位尖晶石NiRh $_{\text 2}$ O $_{\text 4}$的启发,我们研究了金刚石晶格上受抑的$J_1$ - $J_2$海森堡模型在改变自旋长度$S$时的经典到量子交叉。应用最近开发的赝自旋泛函重整化群(pf-FRG)方法任意自旋$S$磁体,我们发现,系统与$S \geq 3/2$驻留在经典制度的低温物理是由共面螺旋的形成和热(有序无序)过渡为主。对于较小的局部矩$S$ =1或$S$ =1/2,我们发现,该系统避免了热有序转变,并形成量子螺旋自旋液体的波动被限制在特征动量空间表面。对于NiRh $_{\text 2}$ O $_{\text 4}$的四元相,一个改进的$J_1$ - $J_2^-$交换模型被发现有利于传统的有序Néel状态(对于任意自旋$S$),即使在一个强的局部单离子自旋各向异性的存在下,它需要额外的挫折源来解释实验观察到的热有序转变的缺乏。

英文摘要:

Motivated by the recent synthesis of the spin-1 A-site spinel NiRh$_{\text 2}$O$_{\text 4}$, we investigate the classical to quantum crossover of a frustrated $J_1$-$J_2$ Heisenberg model on the diamond lattice upon varying the spin length $S$. Applying a recently developed pseudospin functional renormalization group (pf-FRG) approach for arbitrary spin-$S$ magnets, we find that systems with $S \geq 3/2$ reside in the classical regime where the low-temperature physics is dominated by the formation of coplanar spirals and a thermal (order-by-disorder) transition. For smaller local moments $S$=1 or $S$=1/2 we find that the system evades a thermal ordering transition and forms a quantum spiral spin liquid where the fluctuations are restricted to characteristic momentum-space surfaces. For the tetragonal phase of NiRh$_{\text 2}$O$_{\text 4}$, a modified $J_1$-$J_2^-$-$J_2^\perp$ exchange model is found to favor a conventionally ordered Néel state (for arbitrary spin $S$) even in the presence of a strong local single-ion spin anisotropy and it requires additional sources of frustration to explain the experimentally observed absence of a thermal ordering transition.

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