Viret M, Ott F, Renard J P, Glättli H, Pinsard-Gaudart L, Revcolevschi A
Service de Physique de l'Etat Condensé, DSM/DRECAM-CNRS URA 2464, CEA-Saclay, 91191 Gif-sur-Yvette cedex, France.
Phys Rev Lett. 2004 Nov 19;93(21):217402. doi: 10.1103/PhysRevLett.93.217402.
The magnetic phase separation in single crystals of the Pr0.67Ca0.33MnO3 manganites is studied using polarized small angle neutron scattering. The measured spectra give a fractal dimension consistent with a configuration in ferromagnetic filaments of nanometric diameter. We argue here that localized charge carriers hop in a random walk fashion mediating a ferromagnetic "hopping exchange" which coexists with superexchange to create the filamentary phase separation. The arguments for this physical picture are validated by Monte Carlo simulations, where magnetism and transport are treated in a self-consistent manner.
利用极化小角中子散射研究了Pr0.67Ca0.33MnO3锰氧化物单晶中的磁相分离。测量光谱给出的分形维数与纳米直径的铁磁细丝结构一致。我们在此认为，局域电荷载流子以随机游走的方式跳跃，介导了一种与超交换共存的铁磁“跳跃交换”，从而产生丝状相分离。这种物理图像的观点通过蒙特卡罗模拟得到了验证，其中磁学和输运是以自洽的方式处理的。
