Magnetic Instability of Ultrathin fccFexNi1−xFilms

Abstract

The "invar effect" in Fe x Ni 12x alloys occurs when the Fe content approaches 65%. At this point, the magnetization falls to zero, and a martensitic structural transformation from a fcc to a bcc lattice occurs. This paper addresses the question: "What happens if the structural transformation is suppressed in an ultrathin alloy film?" We present results to this effect, showing the variation of the magnetization with changing composition in ultrathin films grown on Cu(100). We find a new low-spin, ferromagnetic phase of matter, which is a sensitive function of the atomic volume. [S0031-9007(97)

Surface-sensitive, element-specific magnetometry with x-ray linear dichroism

“…[ 18-211. This is also true for FexNil-x /Cu( 100) alloy films as previously reported [8]. We suspect that the FexNil-x(111) films investigatec by Freeland et al have not the same atomic volume as our films for Fe concentrations larger than 65'%.…”

“…For photoemission dichroism of the 3p core levels we utilized 190 eV photons (p-polarized) and collected electrons in normal emission with an angular resolution of 2". The angle of incidence of the photon beam was 60" with respect to the surface normal and the magnetization was in the 'transverse' geometry [8,10]. A field pulse from a coil near the sample magnetized the sample along the 001 direction.…”

Investigations of magnetic overlayers at the Advanced Photon Source

“…Ultra-thin films of Fe and Co were grown on Cu(100) as in previous studies [1][2][3][4][5][6][7]. The films exhibited a p(1x1) LEED pattern and no observable contamination as judged Ultimately, the goal was the performance of the double polarization experiment upon the 2p levels.…”

“…[12] Hs is the exchange splitting, obtained in part from scaling from the magnetic moments of each element. [5,7] …”

“…[1][2][3][4][5][6][7] Over time, it became apparent that the most demanding experiment, the double polarization photoelectron spectroscopy or "complete experiment," could best attempted at Beam-line 4 at the Advanced…”