Optical and spin-selective time-of-flight measurement of light-induced desorption of Rb from Fe[Formula: see text]O[Formula: see text] surfaces.

Light-induced desorption of Rb atoms from a ferrimagnetic Fe[Formula: see text]O[Formula: see text](001) surface was studied using a spin-selective optical method, which provides information on the spin polarization, velocity distribution, and amount of the desorbed atoms. The results showed that the intensity of the desorption of Rb from Fe[Formula: see text]O[Formula: see text](001) induced by ultraviolet (UV) light irradiation was smaller than the detection limit at coverages lower than the threshold coverage at which the desorption rate began to increase. Moreover, the average magnetic quantum number of the desorbed atoms was smaller than that of electrons at the Fermi level of the Fe[Formula: see text]O[Formula: see text](001) surface. These indicate that the light-induced desorption of Rb from an Fe[Formula: see text]O[Formula: see text](001) surface occurs only in the high-coverage region in which the desorbing atoms are not in contact with the Fe[Formula: see text]O[Formula: see text] surface, and that the desorption does not involve spin transfer.

Reduction in magnetic coercivity of Co nanomagnets by Fe alloying.

We measured the magnetic hysteresis and coercivity of individual Co and Co0.8Fe0.2 bilayer nano-sized island structures formed on Cu (111) substrate using spin-polarized scanning tunneling microscopy. From the hysteresis taken on various sizes of islands, we found that the alloyed islands are ferromagnetic with out-of-plane magnetic anisotropy, same as the pure islands. Coercivity of the alloy islands, which is dependent on their size, was significantly reduced to ≈40% of that of the pure islands. Based on the Stoner-Wohlfarth model, we evaluated the amount of magnetic anisotropic energy and anisotropy constant for both pure and alloy islands. Since tunneling spectra taken on the alloy islands show upward shifts of the valence electronic states as compared to the pure ones, fewer electrons populated in the valence band of the alloy islands are presumably responsible for the reduction in the magnetic anisotropic energy.

Bulk ferromagnetic tips for spin-polarized scanning tunneling microscopy.

We characterized the performance of electrochemically etched bulk Fe and Ni tips as a probe of spin-polarized scanning tunneling microscopy (SP-STM). Through the observation of the striped contrast on the conical spin-spiral structure formed in Mn double layers on a W(110) substrate, the capability of both the tips to detect the magnetic signal was clarified. We also confirmed that the magnetized direction of the Fe and Ni tips can be flipped between the two out-of-plane directions by external magnetic fields. Our results demonstrate that the ex-situ prepared tips are reliable in SP-STM for the samples that are not susceptible to a stray magnetic field.