III–V based magnetic(GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices

Abstract

III–V based magnetic (GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices (SLs) have been grown by low-temperature molecular beam epitaxy. X-ray diffraction measurements show that the SLs have good crystalline quality and abrupt interfaces. The SLs having relatively wide (Ga,Mn)As layers (⩾70 Å) are found to be ferromagnetic at low temperatures, while the SLs with narrow (Ga,Mn)As layers (⩽50 Å) are paramagnetic even at 2.0 K. Magneto-optic spectra have revealed that, due to the quantum confinement effect, the interband transition energy at Γ is blue shifted with decreasing the thickness of the (Ga,Mn)As and some subbands are formed.

The essential role of carefully optimized synthesis for elucidating intrinsic material properties of (Ga,Mn)As

“…6e) give the same D ¼ 2.43 ± 0.15 meV nm 2 . Identical value of the spin stiffness was also obtained from measurements in an optimized epilayer grown with the same doping and thickness of 18 nm in which we detected the frequencies f 0 and f 1 and applied equation (2). These measurements confirm the reliability of extracted values of the spin stiffness.…”

“…To circumvent the solubility problem, a non-equilibrium, low-temperature molecular-beam-epitaxy (LT-MBE) technique was employed, which led to first successful growths of (Ga,Mn)As ternary alloys with more than 1% Mn and to the discovery of ferromagnetism in these materials [1][2][3][4] . The compounds qualify as ferromagnetic semiconductors to the extent that their magnetic and other properties can be altered by the usual semiconductor electronics engineering variables, such as doping, electric fields, or light.…”

Diluted Magnetic III-V Semiconductors

“…The d-d exchange integral was estimated to be JNN = -1.6 K, which is less than for the corresponding II-VI DMS [12]. On the other hand, for some other (p-type) InMnAs and GaMnAs epilayers FM interaction between Mn ions was observed [20,30,17,18,23]. Magnetization saturates much faster with magnetic field than expected for isolated ions, which is a signature of FM coupling between the ions.…”

“…Only the application of MBE methods resulted in crystals with few molar percent of Mn [10][11][12][13][14][15][16][17][18][19][20][21][22]. Both quasi 3D epilayers, as well as quantum structures were obtained [18]. A very attractive feature of Mn-based III-V DMS is hole induced FM [20,17,19,23].…”

“…For a long time these materials were unavailable, since it was not possible to obtain III-V crystals with a reasonable concentration of magnetic ions. Only the application of MBE methods resulted in crystals with few molar percent of Mn [10][11][12][13][14][15][16][17][18][19][20][21][22]. Both quasi 3D epilayers, as well as quantum structures were obtained [18].…”