Paulsen C, Giblin S R, Lhotel E, Prabhakaran D, Matsuhira K, Balakrishnan G, Bramwell S T
Institut Néel, C.N.R.S-Université Grenoble Alpes, BP 166, 38042, Grenoble, France.
School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, UK.
Nat Commun. 2019 Apr 3;10(1):1509. doi: 10.1038/s41467-019-09323-6.
Extensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: magnetic monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with magnetic monopoles to resonance, allowing the monopoles to hop and transport magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.
在单分子磁体方面的大量研究已经确定了一种基本的弛豫模式，这种模式源于近独立且准经典磁偶极子的核自旋辅助量子隧穿。在此，我们表明核自旋辅助量子隧穿还可以控制纯涌现激发的动力学：自旋冰中的磁单极子。我们的低温实验是在具有广泛核自旋值的典型自旋冰材料上进行的。通过测量磁弛豫或单极子电流，我们提供了有力证据，证明与超精细场的动态耦合使与磁单极子相关的电子自旋达到共振，从而使单极子能够跳跃并传输磁荷。我们的结果展示了电子自旋与核自旋的耦合如何可用于控制单极子电流。它拓宽了辅助量子隧穿机制的相关性，从单分子自旋扩展到强关联系统中的涌现激发。
