Rüegg Ch, Normand B, Matsumoto M, Furrer A, McMorrow D F, Krämer K W, Güdel H-U, Gvasaliya S N, Mutka H, Boehm M
London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom.
Phys Rev Lett. 2008 May 23;100(20):205701. doi: 10.1103/PhysRevLett.100.205701. Epub 2008 May 21.
We follow the evolution of the elementary excitations of the quantum antiferromagnet TlCuCl3 through the pressure-induced quantum critical point, which separates a dimer-based quantum disordered phase from a phase of long-ranged magnetic order. We demonstrate by neutron spectroscopy the continuous emergence in the weakly ordered state of a low-lying but massive excitation corresponding to longitudinal fluctuations of the magnetic moment. This mode is not present in a classical description of ordered magnets, but is a direct consequence of the quantum critical point.
我们追踪了量子反铁磁体TlCuCl₃的元激发在压力诱导的量子临界点附近的演化，该量子临界点将基于二聚体的量子无序相和长程磁有序相分隔开来。我们通过中子光谱证明，在弱有序状态下持续出现一种对应于磁矩纵向涨落的低能但有质量的激发。这种模式在有序磁体的经典描述中并不存在，而是量子临界点的直接结果。
