Thermal and Dynamic Effects in Langevin Simulation of Hysteresis in Nanoscale Pillars.pdfVIP

Thermal and Dynamic Effects in Langevin Simulation of Hysteresis in Nanoscale Pillars 1 0 a a a,b Gregory Brown , M.A. Novotny , and P.A. Rikvold 0 2 a School of Computational Science and Information Technology, Florida State University, y a M Tallahassee, Florida 32306-4120 4 b Center for Materials Research and Technology, and Department of Physics, Florida State 1 University, Tallahassee, Florida 32306-4350 ] i c (February 1, 2008) s - l Dynamic quantities related to hysteresis have been measured in micro- r t m magnetic simulations of single-domain nanoscale magnets at nonzero tempera- . t a ture. The hysteresis-loop area and magnetization-field correlation display the m - characteristics of resonance, and the resonance frequency is found to be tem- d n o perature dependent. The period-averaged magnetization displays symmetry c [ breaking at high frequencies. 1 v Keywords: thermal, hysteresis, resonance, micromagnetic 9 7 The common theme in hysteretic systems is a nonlinear, irreversible response that lags 2 5 0 behind an applied force. While different physical mechanisms may cause this behavior, 1 0 in many interesting situations it results from a system with two local free-energy minima / t a m separated by a free-energy maximum. For instance, the crystalline or shape anisotropy - d of a magnetic particle may create a barrier that significantly in