Cyclotron resonance in ferromagnetic InMnAs and InMnSb

Abstract

We present experimental and theoretical studies of the magneto-optical properties of p-type In 1−x Mn x As and In 1−x Mn x Sb ferromagnetic semiconductor films in ultrahigh magnetic fields oriented along [001]. Samples were fabricated by molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE). To model the results, we used an 8-band Pidgeon-Brown model generalized to include the wave vector dependence of the electronic states along k z as well as the s-d and p-d exchange interactions with the localized Mn d electrons. The Curie temperature is taken as an input parameter and the average Mn spin is treated in mean-field theory. We compared Landau level and band structure calculations with observed cyclotron resonance (CR) measurements. While differences between the CR measurements are seen for MBE and MOVPE samples, our calculations indicate that they arise from differences in the carrier densities. In addition, the difference in the carrier densities suggests significantly larger average spin for the MOVPE structures; this fact could be responsible for higher Curie temperatures in this material system.

High-field magnetic circular dichroism in ferromagnetic InMnSb and InMnAs: Spin-orbit-split hole bands andgfactors

“…This is thought to be due to the fact that in MOVPE grown samples, there are local formations of Mn dimers, trimers and tetramers [15,16] which lowers the hole density and the Fermi Energy. As a result of a lower hole density in the MOVPE grown NGFS, an earlier study estimated that a larger average spin polarization, compared to the MBE grown structure, can be achieved [17]. This fact could be responsible for the higher T c in the MOVPE grown structures.…”

Probe of the Band Structure of MBE Grown p-Type InMnAs at Ultrahigh Magnetic Fields

“…But most of the current research activities in the area of magnetic semiconductors, have been focused on III-Mn-V alloys such as GaMnAs, 2,3 with large valence band e®ective masses; therefore, it is important in this context to explore the opposite extremes of the III-Mn-V ternaries i.e., InMnAs with smaller e®ective mass and larger spin-orbit couplings. 4,5 Probing the bandstructure of In 1Àx Mn x As dilute magnetic semiconductors (DMSs) is important for designing ferromagnetic heterostructures, which may in turn prove useful in the fabrication of spintronic devices. 2,3,[6][7][8][9][10][11] Furthermore, carrier-induced ferromagnetism in III-V semiconductors 8,12,13 and the interaction with the localized spins of magnetic impurities have been studied extensively, 14,15 but the nature of these valence band holes is still an open question.…”

Magnetooptical study of Zeeman effect in Mn modulation-doped InAs/InGaAs/InAlAs quantum well structures

“…[1][2][3][4][5] Diluted magnetic semiconductors (DMS) based on narrow-gap III-V compounds, and, in particular, InMnAs, are considered to be promising candidates for application due to a relatively high Curie temperature and the strong spin-orbit interaction. 6,7 While InAs-based DMS systems with strong spin-orbit coupling have been realized and show very interesting magnetotransport [8][9][10] and opto-electronic properties, [11][12][13][14][15] direct measurements of the giant Zeeman splitting by means of polarized magneto-photoluminescence (PL) have not been reported so far. This is primary caused by the fact that the doping of III-V compounds by Mn atoms generates numerous lattice defects (even if they are partially removed by annealing 7 ) and, consequently, to a drastic decrease of the radiation efficiency.…”