Investigation of a novel material for magnetoelectronics: Co₂Cr_0.6Fe_0.4Al

Abstract

Heusler compounds are promising candidates for future spintronics device applications. The electronic and magnetic properties of Co 2 Cr 0.6 Fe 0.4 Al, an electron-doped derivative of Co 2 CrAl, are investigated using circularly polarized synchrotron radiation and photoemission electron microscopy (PEEM). Element specific imaging reveals needle shaped Cr rich phases in a homogeneous bulk of the Heusler compound. The ferromagnetic domain structure is investigated on an element-resolved basis using x-ray magnetic circular dichroism (XMCD) contrast in PEEM. The structure is characterized by micrometre-size domains with a superimposed fine ripple structure; the lateral resolution in these images is about 100 nm. The domains look identical for Co and Fe giving evidence of a ferromagnetic coupling of these elements. No ferromagnetic contrast is observed at the Cr line. Magnetic spectroscopy exploiting XMCD reveals that the lack of magnetic moment, detected in a SQUID magnetometer, is mainly due to the moment of the Cr atom.

Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers

“…36 This is found easily if comparing the here shown photoelectron spectra and dichroism to previously reported XMCD spectra of Fe containing Heusler compounds [37][38][39] where the XMCD spectra and dichroism appear rather without any resolved splitting of the L 2;3 lines.…”

Electronic structure and spectroscopy of the quaternary Heusler alloy Co2Cr1−xFexAl

“…4 Al is of special interest because a relatively high magneto-resistance ratio of up to 30% was found in powder samples in a small magnetic field of 0.1T [23,24]. Thin films of the compound were successfully grown by several groups [25][26][27][28].…”

Hard X-ray photoelectron spectroscopy on buried, off-stoichiometric Co x Mn y Ge z (x:z=2:0.38) Heusler thin films

“…4 Al has attracted emerged interest as potential material for magnetoelectronics, due to the large MR 8,9 . The band structure calculations confirmed the halfmetallic state of this compound in the ordered L2 1 structure 5,6,8 . Recently, several groups developed fully epitaxial magnetic tunnel junctions (MTJs) based on Co 2 Cr 0.6 Fe 0.…”

“…Furthermore, partially substitution of one of the elements in the ternary Heusler T 2 T ′ M (where, T, T ′ is transition metals and M main group element) can be used to design new materials with predictable properties 5,6 , such as tuning the Fermi energy in to the middle of the minority band gap 7 . The partially substitution of the elements in T 2 T ′ M leads to substitutional quaternary alloys of the type…”