Nature of the magnetic and structural phase transition in MnAs/GaAs(001)

Journal article

In the bulk the structural and magnetic phase transitions between α- and β-MnAs are coupled and proceed abruptly by first order. In heteroepitaxially constrained MnAs/GaAs(001) films, on the other hand, the two phases coexist at 10-40 °C and the magnetization decreases continuously with temperature. We present detailed magnetic measurements on MnAs/GaAs(001) in the phase transition region covering the ferromagnetic a phase, the paramagnetic β phase and the α + β coexistence region. The coexistence of two magnetically distinguishable types of α-MnAs around the onset of the coexistence region at 10 °C, the occurrence of metastable magnetic properties, and the absence of a Curie-Weiss peak in the susceptibility point to a first order of the magnetic phase transition also in thin films. The two types of α-MnAs are characterized by different coercivity and magnetic anisotropy, the latter due to a change in shape anisotropy of the striped phase.

Authors: Ney, A; Hesjedal, T; Pampuch, C; Das, A; Daweritz, L

• Publication status: Published
• Journal: Physical Review B
• Volume: 69
• Issue: 8
• Pages: 813061-813064
• Publication date: 2004-02-01
• DOI: 10.1103/PhysRevB.69.081306
• EISSN: 1550-235X
• ISSN: 1098-0121
• Language: English