Ga1−xMnxN epitaxial films with high magnetization

Abstract

We report on the fabrication of pseudomorphic wurtzite Ga1−xMnxN grown on GaN with Mn concentrations up to 10% using molecular beam epitaxy. According to Rutherford backscattering, the Mn ions are mainly at the Ga-substitutional positions, and they are homogeneously distributed according to depth-resolved Auger-electron spectroscopy and secondary-ion mass-spectroscopy measurements. A random Mn distribution is indicated by transmission electron microscopy, and no Mn-rich clusters are present for optimized growth conditions. A linear increase of the c-lattice parameter with increasing Mn concentration is found using x-ray diffraction. The ferromagnetic behavior is confirmed by superconducting quantum-interference measurements showing saturation magnetizations of up to 150 emu/cm3.

Theory of ferromagnetism driven by superexchange in dilute magnetic semi-conductors

“…Recent progress in epitaxy, contamination-free processing, and (nano)characterization [2][3][4][5] allowed the preparation of Ga 1−x Mn x N films with the randomly distributed Mn 3+ ions up to x = 0.1 showing T C up to about 13 K [6] despite the absence of itinerant carriers. A high degree of crystallinity, a random distribution of the Mn ions, and a weak degree of compensation by residual donors were checked in these samples by a range of electron microscopy, synchrotron radiation, ion beam, optical, and magnetic resonance techniques [2,3,5].…”

“…A high degree of crystallinity, a random distribution of the Mn ions, and a weak degree of compensation by residual donors were checked in these samples by a range of electron microscopy, synchrotron radiation, ion beam, optical, and magnetic resonance techniques [2,3,5].…”

Two-Probe Measurements of Electron Transport in GaN:Si/(Ga,Mn)N/GaN:Si Spin Filter Structures

“…While the search for a technology-viable magnetic semiconductor at room temperature is still the subject of active research a great deal of knowledge on the underlying physical processes can be gained from the investigation of various systems at their relevant temperatures [1]. Our material of choice is (Ga,Mn)N -an emerging ferromagnetic semiconductor whose long range ferromagnetic ordering has been confirmed at the low end of cryogenic temperatures [2,3]. The importance of GaN-based compounds and heterostructures stems from the growing significance of wide band-gap materials in conventional electronics, particularly in opto-and high power electronics.…”

Colossal magnetic moment in Cr and Er co-implanted GaN films

“…Furthermore, the carrier-induced RKKY ferromagnetic interaction may be able to work [25], with the necessary condition that the carrier concentration is greater than 1 Â 10 20 cm À3 . However, in our samples, the carrier concentration is far below that value, therefore the RT ferromagnetism cannot be attributed to the carrier-induced RKKY ferromagnetic interaction, but may be well explained by the bound magnetic polaron (BMP) theory [26][27][28][29]. Although a high carrier density is not necessary in the BMP model, it does require high-density spin polarized impurities, mediating the exchange interactions between BMPs.…”