Epitaxial growth of the diluted magnetic semiconductors CryGe1−y and CryMnxGe1−x−y

Abstract

We report the epitaxial growth of CryGe1−y and CryMnxGe1−x−y(001) thin films on GaAs(001), describe the structural and transport properties, and compare the measured magnetic properties with those predicted by theory. The samples are strongly p type, and hole densities increase with Cr concentration. The CryGe1−y system remains paramagnetic for the growth conditions and low Cr concentrations employed (y⩽0.04), consistent with density functional theory predictions. Addition of Cr into the ferromagnetic semiconductor MnxGe1−x host systematically reduces the Curie temperature and total magnetization.

Surface characterization ofMnxGe1−xandCryGambardella1, Claude2, Rusponi3 et al. 2007Phys. Rev. BSelf Cite361270View full textAdd to dashboardCite

“…The Mn concentrations were determined by small-spot transmission electron microscopy analysis of the interior of the film. 2 The magnetization measured by superconducting quantum interference device ͑SQUID͒ prior to the XAS measurements as a function of temperature and applied field was consistent with previously reported data, 2,6 displaying remanent ferromagnetism at 5 K, as shown in Fig. 1.…”

“…The addition of Cr was investigated in order to increase the hole density and enhance the magnetization characteristics of Mn x Ge 1−x , but was shown to systematically reduce the Curie temperature and saturation magnetization of the mixed compounds. 6 In light of these observations, it is interesting to know whether Cr has a magnetic moment antiferromagnetically coupled to Mn or no net magnetization. Here we show that Cr possesses a paramagnetic moment only when oxidized ͓TEY data in Fig.…”

“…515A and 516 in Ref. 6. The Mn concentrations were determined by small-spot transmission electron microscopy analysis of the interior of the film.…”

“…4,5 Although most activity is focused on group III-Mn-V materials, there is steadily increasing interest in Ge-based DMS, driven by their potential integration in standard Si semiconductor technology. 2,[6][7][8][9][10][11][12][13] Several growth techniques have been employed to produce MnGe compounds, including low-temperature molecular beam epitaxy ͑MBE͒, 2,6-9 furnace melting, 14,15 and implantation of high-energy Mn 2+ ions into single crystal Ge wafers. [16][17][18] The investigation of the magnetic properties of MnGe compounds, however, reveals very significant differences depending on the growth method.…”

Magneto-optical properties of group-IV ferromagnetic semiconductor Ge1−xFex grown by low-temperature molecular beam epitaxy

“…They also demonstrated the anomalous Hall effect with carrier-induced magnetization control of the Ge 1-x Mn x films by applying gate voltages. There are also several reports that focused on Ge-based ferromagnetic semiconductors [10][11][12], including high Curie temperatures close to room temperature [13][14][15]. Nevertheless, owing to the lack of direct evidence for the spin splitting of their band structure induced by s,p-d exchange interactions, the origin of their ferromagnetism has been still under investigation [16].…”