Collective character of spin excitations in a system of Mn$^{2+}$ spins coupled to a two-dimensional electron gas

TL;DR

This study investigates low energy spin excitations in Mn-doped CdTe quantum wells, revealing a large Knight shift and potential magnetic field-induced ferromagnetic order, aligning with recent theoretical predictions.

Contribution

It provides experimental evidence of collective spin behavior and magnetic ordering in Mn-doped quantum wells, supporting theoretical models.

Findings

Large Knight shift observed at specific magnetic fields

Evidence of magnetic field-induced ferromagnetic order

Agreement with recent theoretical predictions

Abstract

We have studied the low energy spin excitations in n-type CdMnTe based dilute magnetic semiconductor quantum wells. For magnetic fields for which the energies for the excitation of free carriers and Mn spins are almost identical an anomalously large Knight shift is observed. Our findings suggests the existence of a magnetic field induced ferromagnetic order in these structures, which is in agreement with recent theoretical predictions [J. K{\"o}nig and A. H. MacDonald, submitted Phys. Rev. Lett. (2002)]