Thin film quantum materials

Abstract:

This book presents the latest research in this frontier field.

Abstract:

We present an analytic solution for the magnetic field of a bar-shaped permanent magnet. Assuming a constant magnetization, we derive expressions for the stray field in three dimensions. The analytic solutions can be readily applied to field calculation problems for magnetic force microscopy simulations without the need for finite element methods. © 2005 American Institute of Physics.

Abstract:

Manganese arsenide is a promising candidate for new spintronics applications since it is ferromagnetic at room temperature and can be grown with high epitaxial quality on semiconductors. However, the transition temperature of ∼40 °C is a limiting factor for device applications. Since the coupled magnetic and structural transition is of first order, it is in principle possible to shift the transition temperature by changing external parameters. Here we show that by either applying an external magnetic field or by growing the MnAs films on GaAs(1 1 1), i.e., by changing the epitaxial constraints which are equivalent to external pressure, ferromagnetic order can be stabilized well above the bulk-phase transition temperature. © 2004 Elsevier B.V. All rights reserved.

Abstract:

We provide the first direct evidence of interactions in a self-organized pattern of coexisting ferromagnetic and paramagnetic MnAs stripe domains as a function of the coupling strength between the stripes (inter) and within one stripe (intra). The value of the intra exchange constant A = 17.7 × 1010 erg/cm is determined unambiguously from spin wave resonance. Additionally, in-plane ferromagnetic resonance measurements reveal the presence of a strong coupling between the neighboring stripes, which can dominate the weak intra-stripe interaction.