High-quality GaMnAs films grown with arsenic dimers

Campion, R. P.; Edmonds, K. W.; Zhao, Lixia; Wang, K.Y; Foxon, C. T.; Gallagher, B. L.; Staddon, C. R.

doi:10.1016/s0022-0248(02)01939-5

Cited by 93 publications

(65 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Mn concentration was controlled by varying the calibrated Mn/Ga ratio, and confirmed by x-ray fluorescence and xray diffraction measurements. Full details of the growth and structural characterisation are presented elsewhere [6]. In agreement with previous studies, a significant increase in T C was obtained by annealing at low temperatures (≈180ºC in the present case).…”

Section: Abstract the Resistivity Temperature And Magnetic Field Dsupporting

confidence: 90%

Magnetoresistance and Hall effect in the ferromagnetic semiconductor Ga1−xMnxAs

Edmonds

Campion

Wang

et al. 2003

Journal of Applied Physics

View full text Add to dashboard Cite

Abstract. The resistivity, temperature, and magnetic field dependence of the anomalous Hall effect in a series of metallic Ga 1-x Mn x As thin films with 0.015≤ x ≤0.08 is presented. A quadratic dependence of the anomalous Hall resistance on the resistivity is observed, with a magnitude which is in agreement with Berry phase theories of the anomalous Hall effect in dilute magnetic semiconductors.In III-V dilute magnetic semiconductors such as Ga 1-x Mn x As, the ferromagnetic interaction between localised spins is mediated by the itinerant valence band electrons [1]. The participation of the free carriers in the magnetism results in a large anomalous Hall effect (AHE). The total Hall resistance is given byThe normal Hall term ρ NH and the anomalous Hall term ρ AH are proportional to the perpendicular components of the external magnetic field, B z , and the magnetisation, M z , respectively. The measured Hall resistance therefore contains information on both the magnetism and the carrier concentration p. However, separate extraction of this information is complicated by the field dependence of the resistivity ρ and the anomalous Hall coefficient R A (ρ), so that obtaining accurate values for the hole density in Ga 1-x Mn x As requires high magnetic fields and highly metallic samples [1,2]. A better understanding of the factors affecting the AHE is therefore desirable. The AHE is usually ascribed to a scattering anisotropy induced by the spin-orbit interaction [3]. Skew and side-jump descriptions give R A α ρ and R A α ρ 2 respectively, where ρ is the longitudinal resistance. The skew scattering picture is usually assumed in Ga 1-x Mn x As [1], although a quadratic dependence on ρ has been observed for In 0.88 Mn 0.12 As [4]. It was recently proposed that the AHE in the III-V ferromagnetic semiconductors is dominated by a disorder independent contribution which is due to a Berry phase acquired by the itinerant electrons, and results in a fieldindependent anomalous Hall conductivity [5]. In the following, we present measurements of the anomalous Hall effect in a series of metallic Ga 1-x Mn x As samples as a function of magnetic field and temperature, and compare our results to the predictions of reference [5]. 45nm thick Ga 1-x Mn x As films with 0.015≤ x ≤0.08 were grown on GaAs(001) by low temperature molecular beam epitaxy. The Mn concentration was controlled by varying the calibrated Mn/Ga ratio, and confirmed by x-ray fluorescence and xray diffraction measurements. Full details of the growth and structural characterisation are presented elsewhere [6]. In agreement with previous studies, a significant increase in T C was obtained by annealing at low temperatures (≈180ºC in the present case). This procedure resulted in a T C of up to 132K for x=0.06, as well as a reduction in the resistivity and magnetoresistance. Across the whole range of Mn doping studied, the samples are in the so-called 'metallic' regime, with conductivities in the range (200-700)Ω -1 cm -1 at low temperatures [2]. Magnetoresistance and Hal...

show abstract

Section: Abstract the Resistivity Temperature And Magnetic Field Dsupporting

confidence: 90%

Magnetoresistance and Hall effect in the ferromagnetic semiconductor Ga1−xMnxAs

Edmonds

Campion

Wang

et al. 2003

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…This leads to an upper temperature limit for successful growth when the Mn surface concentration approaches a significant proportion of a monolayer, after which point surface clustering of Mn occurs, frustrating the growth. 60,61 Furthermore, higher Mn fluxes require lower growth temperatures.…”

Section: Discussionmentioning

confidence: 99%

“…Full details of the growth are presented elsewhere. 60,61 The Mn content was controlled by varying the Mn/ Ga incident flux ratio, measured in situ and calibrated using secondary-ion-mass spectroscopy ͑SIMS͒ measurements on 1 m thick ͑Ga,Mn͒As films, grown under otherwise identical conditions to the samples considered here. A detailed comparison of the results of a number of different calibration techniques, presented in Ref.…”

Section: Experiments a Measured Curie Temperatures And Hole Densmentioning

confidence: 99%

Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors

et al. 2005

View full text Add to dashboard Cite

We report on a comprehensive combined experimental and theoretical study of Curie temperature trends in ͑Ga,Mn͒As ferromagnetic semiconductors. Broad agreement between theoretical expectations and measured data allows us to conclude that T c in high-quality metallic samples increases linearly with the number of uncompensated local moments on Mn Ga acceptors, with no sign of saturation. Room temperature ferromagnetism is expected for a 10% concentration of these local moments. Our magnetotransport and magnetization data are consistent with the picture in which Mn impurities incorporated during growth at interstitial Mn I positions act as double-donors and compensate neighboring Mn Ga local moments because of strong nearneighbor Mn Ga u Mn I antiferromagnetic coupling. These defects can be efficiently removed by post-growth annealing. Our analysis suggests that there is no fundamental obstacle to substitutional Mn Ga doping in high-quality materials beyond our current maximum level of 6.8%, although this achievement will require further advances in growth condition control. Modest charge compensation does not limit the maximum Curie temperature possible in ferromagnetic semiconductors based on ͑Ga,Mn͒As.

show abstract

“…[13]. The films are grown on GaAs(001) substrates by low temperature (≈200ºC) molecular beam epitaxy.…”

Section: We Present a Combined Theoretical And Experimental Study Of mentioning

confidence: 99%