Hunting Majorana Fermions in Kitaev Magnets
Hunting Majorana Fermions in Kitaev Magnets
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DOI：
10.7566/jpsj.89.012002
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发表时间：
2019-09
影响因子：
1.7
通讯作者：
Y. Motome;J. Nasu
中科院分区：
文献类型：
--
作者：
Y. Motome;J. Nasu
马约拉纳费米子是一种费米子粒子，它本身就是反粒子。自1937年理论发现以来，粒子物理学一直在寻找奇异粒子。然而，在过去的几十年里，它重新引起了人们对凝聚态物理学的兴趣，在那里它可以作为物质量子态的基本激发（准粒子）来实现。在这篇综述中，我们讨论了马约拉纳费米子的另一个平台，量子自旋液体，在强量子涨落的最低温度下相互作用磁矩保持无序。它们具有拓扑纠缠和分数激励的特点，近年来对其在拓扑量子计算中的应用进行了深入的讨论。作为这种奇异态的主要候选者，我们在这里聚焦于基塔耶夫磁体，它是自旋轨道莫特绝缘体的一个亚群。在简要概述了基塔耶夫模型和精确基态自旋的分数化之后，我们回顾了这个快速发展的领域最近的爆炸性发展，重点是基塔耶夫模型在有限温度下的数值解以及与实验的比较。关键的概念是热分馏——两种类型的分馏激发在很大程度上不同的温度下表现出来。这导致不同的热力学和自旋动力学在各种实验可测量的量。我们讨论了分数准粒子的特征等特殊行为，并与基塔耶夫磁体候选材料的现有实验数据进行了仔细的比较。本文综述了基塔耶夫磁体中马约拉纳费米子的识别现状，为进一步对奇异粒子进行拓扑量子计算的实验和理论研究奠定了基础。
A Majorana fermion is a fermionic particle that is its own antiparticle. Since the theoretical discovery in 1937, the exotic particle has long been searched in particle physics. In the last few decades, however, it has attracted renewed interest in condensed matter physics, where it can be realized as an elementary excitation (quasiparticle) in quantum states of matter. In this review, we discuss another platform for Majorana fermions, the quantum spin liquid, in which interacting magnetic moments remain disordered down to the lowest temperature under strong quantum fluctuations. They are characterized by topological entanglement and fractional excitations, whose possible application to topological quantum computation is recently discussed intensively. As a prime candidate for such exotic states, we here focus on the Kitaev magnets, a subgroup of the spin-orbit Mott insulators. After a brief overview of the Kitaev model and the fractionalization of spins in the exact ground state, we review recent explosive development in this rapidly growing field, with a focus on numerical solutions of the Kitaev model at finite temperatures and the comparison with experiments. The key concept is thermal fractionalization --- two types of fractional excitations manifest themselves at largely different temperatures. This leads to distinct thermodynamics and spin dynamics in a variety of experimentally measurable quantities. We discuss such peculiar behaviors as the signatures of fractional quasiparticles, in careful comparison with the available experimental data for the candidate materials of the Kitaev magnets. Our review gives an overview of the current status of the identification of Majorana fermions in the Kitaev magnets, which would serve as a basis for further experimental and theoretical studies toward the manipulation of the exotic particles for topological quantum computation.