Carretta S, Santini P, Amoretti G, Guidi T, Copley J R D, Qiu Y, Caciuffo R, Timco G, Winpenny R E P
Dipartimento di Fisica, Università di Parma, I-43100 Parma, Italy.
Phys Rev Lett. 2007 Apr 20;98(16):167401. doi: 10.1103/PhysRevLett.98.167401. Epub 2007 Apr 16.
Using inelastic neutron scattering and applied fields up to 11.4 T, we have studied the spin dynamics of the Cr7Ni antiferromagnetic ring in the energy window 0.05-1.6 meV. We demonstrate that the external magnetic field induces an avoided crossing (anticrossing) between energy levels with different total-spin quantum numbers. This corresponds to quantum oscillations of the total spin of each molecule. The inelastic character of the observed excitation and the field dependence of its linewidth indicate that molecular spins oscillate coherently for a significant number of cycles. Precise signatures of the anticrossing are also found at higher energy, where measured and calculated spectra match very well.
利用非弹性中子散射以及高达11.4 T的外磁场，我们研究了Cr7Ni反铁磁环在0.05 - 1.6 meV能量窗口内的自旋动力学。我们证明，外磁场会在具有不同总自旋量子数的能级之间诱发一个避免交叉（反交叉）。这对应于每个分子总自旋的量子振荡。所观测到的激发的非弹性特征及其线宽的场依赖性表明，分子自旋会相干地振荡相当多的周期。在更高能量处也发现了反交叉的精确特征，测量光谱与计算光谱在该处非常吻合。
