Charge inhomogeneities and transport in semiconductor heterostructures with a manganese $\delta$-layer

Abstract

We study experimentally and theoretically the effects of disorder, nonlinear screening, and magnetism in semiconductor heterostructures containing a $\delta$-layer of Mn, where the charge carriers are confined within a quantum well and hence both ferromagnetism and transport are two-dimensional (2D) and differ qualitatively from their bulk counterparts. Anomalies in the electrical resistance observed in both metallic and insulating structures can be interpreted as a signature of significant ferromagnetic correlations. The insulating samples turn out to be the most interesting as they can give us valuable insights into the mechanisms of ferromagnetism in these heterostructures. At low charge carrier densities, we show how the interplay of disorder and nonlinear screening can result in the organization of the carriers in the 2D transport channel into charge droplets separated by insulating barriers. Based on such a droplet picture and including the effect of magnetic correlations, we analyze the transport properties of this set of droplets, compare it with experimental data, and find a good agreement between the model calculations and experiment. Our analysis shows that the peak or shoulder-like features observed in temperature dependence of resistance of 2D heterostructures $\delta$-doped by Mn lie significantly below the Curie temperature $T_C$ unlike the three-dimensional case, where it lies above and close to $T_C$. We also discuss the consequences of our description for understanding the mechanisms of ferromagnetism in the heterostructures under study.

13 pages, 12 figures, RevTeX

References in corpus (12)

• Theory of ferromagnetic (III,Mn)V semiconductors
• Impurity Band Conduction in a High Temperature Ferromagnetic Semiconductor
• Curie point singularity in the temperature derivative of resistivity in (Ga,Mn)As
• Interplay between carrier localization and magnetism in diluted magnetic and ferromagnetic semiconductors
• Curie temperature versus hole concentration in field-effect structures of Ga1-xMnxAs
• Tunable spin polarization in III-V quantum wells with a ferromagnetic barrier
• Nonlinear screening and percolative transition in a two-dimensional electron liquid
• Magnetotransport in disordered delta-doped heterostructures
• Hysteretic magnetoresistance and thermal bistability in a magnetic two-dimensional hole system
• Structural and transport properties of GaAs/delta<Mn>/GaAs/InxGa1-xAs/GaAs quantum wells
• Electrostatics of two-dimensional structures: exact solutions and approximate methods
• Lecture Notes on Semiconductor Spintronics

Cited by in corpus (8)

• Electronic phase separation: recent progress in the old problem
• Anomalous Hall effect in a 2D magnetic semiconductor hetereostructure: Evidence of Berry phase effects in the hopping-transport regime
• Materials considerations for forming the topological insulator phase in InAs/GaSb heterostructures
• Resonant exchange interaction in semiconductors
• Indirect exchange interaction between magnetic adatoms in graphene
• Noise studies of magnetization dynamics in dilute magnetic semiconductor heterostructures
• Droplets of the order parameter in a low density attracting electron system in the presence of a strong random potential
• Magnetization in AIIIBV semiconductor heterostructures with the depletion layer of manganese