Critical properties of gapped spin-1/2 chains and ladders in a magnetic field
Critical properties of gapped spin-1/2 chains and ladders in a magnetic field
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DOI：
10.1103/physrevb.55.5816
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发表时间：
1997-03-01
影响因子：
3.7
通讯作者：
Giamarchi, T
中科院分区：
文献类型：
--
作者：
Chitra, R;Giamarchi, T
自旋为1/2的带隙链的一个有趣的特征是，在外加磁场H存在下，它们经历了一个无公度-无公度的转变。系统是在一个无间隙的无公度制度之间的所有值的磁场的下临界场H-c1和上临界场H-c2，当它是无间隙的，并具有幂律相关。我们计算临界指数为这样一个通用的带隙系统在无公度制度在临界场H-C1及其附近。我们的分析也适用于自旋-1/2阶梯。我们计算了有限温度下的全动力学极化率。我们用它讨论了各种模式的热加宽，得到了核自旋弛豫速率T ~（-1）的低温行为。我们讨论了二聚链、阻挫链和自旋-1/2阶梯的特殊情况。
An interesting feature of spin-1/2 chains with a gap is that they undergo a commensurate-incommensurate transition in the presence of an external magnetic field H. The system is in a gapless incommensurate regime for all values of the magnetic field between the lower critical field H-c1 and an upper critical field H-c2, when it is gapless and has power-law correlations. We calculate the critical exponents for such a generic gapped system in the incommensurate regime at the critical field H-c1 and in its vicinity. Our analysis also applies to the spin-1/2 ladder. We compute the full dynamical susceptibilities at finite temperature. We use the same to discuss the thermal broadening of various modes and obtain the low-temperature behavior of the nuclear spin relaxation rate T-1(-1). We discuss the results obtained here for the special cases of the dimerized chain, frustrated chain, and the spin-1/2 ladder.