Rotation Of Spin-Polarization Due To The Verwey Transition At A Surface Of A < 110 >-Oriented Magnetite Whisker Observed By Field-Emitted Electrons Polarimetry

We observed the Verwey transition, metal-insulator transition, in a spin-polarization of field-emitted electrons from a topmost surface of a < 110 >-oriented magnetite whisker by means of field-emitted electrons polarimetry. The measurements of spin polarization of field-emitted electrons from a magnetite whisker were carried out ranging from 40 to 300 K of tip temperature under UHV condition of 3x10(-8) Pa. Raising temperature of the whisker, the polarization increased from 4 to 11 % with a rotation of its direction. The rotation angle corresponds to a change of magnetic easy axis from < 001 > to < 111 > direction caused by the Verwey transition. Our experimental results clarified that the Verwey transition occurs even at a surface as well as in a bulk.