Sologubenko A V, Berggold K, Lorenz T, Rosch A, Shimshoni E, Phillips M D, Turnbull M M
II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany.
Phys Rev Lett. 2007 Mar 9;98(10):107201. doi: 10.1103/PhysRevLett.98.107201. Epub 2007 Mar 5.
We present experiments on the thermal transport in the spin-1/2 chain compound copper pyrazine dinitrate Cu(C4H4N2)(NO3)2. The heat conductivity shows a surprisingly strong dependence on the applied magnetic field B, characterized at low temperatures by two main features. The first one appearing at low B is a characteristic dip located at muBB approximately kBT, that may arise from umklapp scattering. The second one is a plateaulike feature in the quantum critical regime, muB|B - Bc| < kBT, where Bc is the saturation field at T=0. The latter feature clearly points towards a momentum and field-independent mean free path of the spin excitations, contrary to theoretical expectations.
我们展示了关于自旋1/2链状化合物硝酸铜吡嗪Cu(C4H4N2)(NO3)2中热输运的实验。热导率对所施加的磁场B表现出惊人的强烈依赖性，在低温下具有两个主要特征。第一个出现在低磁场B时，是位于μBB≈kBT处的一个特征性凹陷，这可能源于倒逆散射。第二个是量子临界区域μB|B - Bc| < kBT中的一个类似平台的特征，其中Bc是T = 0时的饱和场。后一个特征明显表明自旋激发的平均自由程与动量和场无关，这与理论预期相反。
