Niggemann Nils, Hering Max, Reuther Johannes
Dahlem Center for Complex Quantum Systems and Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
J Phys Condens Matter. 2020 Jan 9;32(2):024001. doi: 10.1088/1361-648X/ab4480.
Quantum spin liquids are long-range entangled phases whose magnetic correlations are determined by strong quantum fluctuations. While an overarching principle specifying the precise microscopic coupling scenarios for which quantum spin-liquid behavior arises is unknown, it is well-established that they are preferably found in spin systems where the corresponding classical limit of spin magnitudes [Formula: see text] exhibits a macroscopic ground state degeneracy, so-called classical spin liquids. Spiral spin liquids represent a special family of classical spin liquids where degenerate manifolds of spin spirals form closed contours or surfaces in momentum space. Here, we investigate the potential of spiral spin liquids to evoke quantum spin-liquid behavior when the spin magnitude is tuned from the classical [Formula: see text] limit to the quantum S = 1/2 case. To this end, we first use the Luttinger-Tisza method to formulate a general scheme which allows one to construct new spiral spin liquids based on bipartite lattices. We apply this approach to the two-dimensional square lattice and the three-dimensional hcp lattice to design classical spiral spin-liquid phases which have not been previously studied. By employing the pseudofermion functional renormalization group (PFFRG) technique we investigate the effects of quantum fluctuations when the classical spins are replaced by quantum S = 1/2 spins. We indeed find that extended spiral spin-liquid regimes change into paramagnetic quantum phases possibly realizing quantum spin liquids. Remnants of the degenerate spiral surfaces are still discernible in the momentum-resolved susceptibility, even in the quantum S = 1/2 case. In total, this corroborates the potential of classical spiral spin liquids to induce more complex non-magnetic quantum phases.
量子自旋液体是长程纠缠相，其磁关联由强量子涨落决定。虽然确定产生量子自旋液体行为的精确微观耦合情形的总体原则尚不清楚，但人们已经清楚地认识到，它们更倾向于出现在自旋系统中，在这些系统中，自旋大小[公式：见正文]的相应经典极限表现出宏观基态简并性，即所谓的经典自旋液体。螺旋自旋液体代表了一类特殊的经典自旋液体，其中自旋螺旋的简并流形在动量空间中形成封闭轮廓或曲面。在这里，我们研究当自旋大小从经典的[公式：见正文]极限调谐到量子S = 1/2情形时，螺旋自旋液体引发量子自旋液体行为的潜力。为此，我们首先使用卢廷格 - 蒂萨方法制定一个通用方案，该方案允许人们基于二分晶格构建新的螺旋自旋液体。我们将此方法应用于二维正方形晶格和三维六方密堆积晶格，以设计先前未研究过的经典螺旋自旋液相。通过采用赝费米子泛函重整化群（PFFRG）技术，我们研究当经典自旋被量子S = 1/2自旋取代时量子涨落的影响。我们确实发现，扩展的螺旋自旋液体区域转变为顺磁量子相，可能实现量子自旋液体。即使在量子S = 1/2情形下，简并螺旋面的残余在动量分辨磁化率中仍然清晰可辨。总的来说，这证实了经典螺旋自旋液体诱导更复杂非磁量子相的潜力。
