Evidence of magnetic domains in the reentrant spin glasses Ni1-xMnx studied by neutron depolarization.

摘要: Polarization analysis of the transmitted beam was performed using a pulsed neutron source in reentrant-spin-glass (RSG) system ${\mathrm{Ni}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$, for concentration range (0.23\ensuremath{\le}x\ensuremath{\le}0.28) encompassing critical concentration. The polarization P measured as function temperature, wavelength, and applied field. Unlike other RSG systems previously studied, decreases at all temperatures below Curie temperature even samples close to This behavior is also observed Fe-Zr alloys. In Ni-Mn wavelength dependence indicates existence magnetic domains, whose size \ensuremath{\delta} decreases, with increasing x, from 10 50 \ensuremath{\mu}m x=0.23 few thousands angstroms x=0.25. No depolarization occurs xg0.25. As shown x=0.23, irreversibilities polarization, which depend on cooling conditions, indicate that domain arrangement freezes low temperature. Clearly, Ni-Mn, drop susceptibility does not result decrease or magnetization domains but slowing down their mobility.