Fermi Surface Manipulation by External Magnetic Field Demonstrated for a Prototypical Ferromagnet

Abstract

We consider the details of the near-surface electronic band structure of a prototypical ferromagnet, Fe(001). Using high-resolution angle-resolved photoemission spectroscopy, we demonstrate openings of the spin-orbit-induced electronic band gaps near the Fermi level. The band gaps, and thus the Fermi surface, can be manipulated by changing the remanent magnetization direction. The effect is of the order of ΔE ¼ 100 meV and Δk ¼ 0.1 Å −1 . We show that the observed dispersions are dominated by the bulk band structure. First-principles calculations and one-step photoemission calculations suggest that the effect is related to changes in the electronic ground state and not caused by the photoemission process itself. The symmetry of the effect indicates that the observed electronic bulk states are influenced by the presence of the surface, which might be understood as related to a Rashba-type effect. By pinpointing the regions in the electronic band structure where the switchable band gaps occur, we demonstrate the significance of spinorbit interaction even for elements as light as 3d ferromagnets. These results set a new paradigm for the investigations of spin-orbit effects in the spintronic materials. The same methodology could be used in the bottom-up design of the devices based on the switching of spin-orbit gaps such as electric-field control of magnetic anisotropy or tunneling anisotropic magnetoresistance.

Localized segregation of gold in ultrathin Fe films on Au(001)

“…6 Thus, it was often the system of choice for studies of ultra-thin film phenomena, such as quantum well states 7,8 and interlayer exchange coupling. [8][9][10] In a recent publication, 5 we demonstrated that in the Fe/Au(001) system it is possible to observe the opening/closing of the magnetizationdependent spin-orbit gaps located near the Fermi level. Clearly, Fe/Au(001) system is well-suited as a model ferromagnet/heavy metal system.…”

“…1,2 This recent finding stimulated the revival of fundamental research on the electronic properties of the ferromagnets interfaced with heavy metals. [3][4][5] One of the possible candidates for such a model system is an Fe film grown on Au(001). Ultra-thin Fe films grown epitaxially on Au(001) have been widely studied because of the very small lattice mismatch < 1 % and epitaxial growth conditions.…”

New Developments in Spin-Dependent Photoemission

“…The four remanent magnetization directions are indicated as "up", "down", "left", and "right", respectively. After [49].…”

“…For this purpose, we used thin Fe films (100 monolayer thick) epitaxially grown on Au(001) in a preparation chamber directly attached to the photoemission system. The films grow in the body-centered structure in perfect registry with the substrate [49], providing a high-quality Fe(001) surface.…”

Quantum-well-induced engineering of magnetocrystalline anisotropy in ferromagnetic films

“…Although interfacial Rashba field is known to affect the interface or surface states, 24 here we demonstrate that it also influences the bulk QWSs and thus impacts the bulk physical properties, agreeing with recent observations. [25][26][27] Since the MCAE oscillation correlates with the Fe-QWS position respecting to E F , the MCAE can be tailored by moderately charging the Fe film to shift E F . We propose that magnitude of MCAE can be modified by several times by charging a Fe film within one electron per unit cell and the magnetization orientation of a 5-MLs Fe film can be switched.…”