Nanosecond magnetization reversal of highly coercive FePt with pulsed microcoils: experiments and modelling

In this paper, the switching of high coercivity material FePt at short timescales is studied. A way to produce magnetic fields that are strong and fast at the same time, is to drive very short current pulses through very small coils. The coils used in this work consist of a single turn of a 30 mum thick copper film with a core diameter of 50 mum. The system is well suited to study the magnetization reversal of highly anisotropic FePt of the L1₀ phase, which is seen as a promising candidate for future high density magnetic recording due to its low critical grain size for superparamagnetism and its corrosion resistance. The FePt films were grown epitaxially by pulsed laser deposition on MgO(100) substrates at 800degC and have coercivities above 5 T in static measurements at room temperature. A hysteresis loop simulation compares well with the measurement.