Rønnow H M, Parthasarathy R, Jensen J, Aeppli G, Rosenbaum T F, McMorrow D F
Laboratory for Neutron Scattering, ETH-Zürich and Paul Scherrer Institut, 5232 Villigen, Switzerland.
Science. 2005 Apr 15;308(5720):389-92. doi: 10.1126/science.1108317.
The excitation spectrum of a model magnetic system, LiHoF4, was studied with the use of neutron spectroscopy as the system was tuned to its quantum critical point by an applied magnetic field. The electronic mode softening expected for a quantum phase transition was forestalled by hyperfine coupling to the nuclear spins. We found that interactions with the nuclear spin bath controlled the length scale over which the excitations could be entangled. This generic result places a limit on our ability to observe intrinsic electronic quantum criticality.
利用中子光谱学研究了模型磁体系统LiHoF₄的激发光谱，该系统通过外加磁场被调节至其量子临界点。超精细耦合到核自旋阻止了量子相变预期的电子模式软化。我们发现，与核自旋库的相互作用控制了激发能够发生纠缠的长度尺度。这一普遍结果限制了我们观察本征电子量子临界性的能力。
