TY - JOUR

T1 - A technique for simulating the effect of long-term magnetic viscosity in permanent magnets

AU - Thompson, P.J.

AU - Street, Robert

PY - 1997

Y1 - 1997

N2 - A technique is presented by which the change in magnetisation at a constant field as a result of long-term magnetic viscosity can be estimated. When an alternating field with an initial amplitude Delta H is superposed upon a bias field H and gradually decreased to zero, a change in the magnetisation at H will result. Utilising Neel's description of magnetic viscosity, in which magnetisation changes are formulated in terms of an effective viscosity field, h(f)(t), superposed on the applied field, we calculate the equivalent waiting time, t, required for h(f)(t) to attain a value equal to Delta H. We propose that the calculated time interval t represents the waiting time at the field H required for viscosity effects to bring about the equivalent change in magnetisation. If the working point of a permanent magnet or magnetic recording medium is known, this technique provides a quantitative estimate of the long-term stability of the magnetic state of the material.

AB - A technique is presented by which the change in magnetisation at a constant field as a result of long-term magnetic viscosity can be estimated. When an alternating field with an initial amplitude Delta H is superposed upon a bias field H and gradually decreased to zero, a change in the magnetisation at H will result. Utilising Neel's description of magnetic viscosity, in which magnetisation changes are formulated in terms of an effective viscosity field, h(f)(t), superposed on the applied field, we calculate the equivalent waiting time, t, required for h(f)(t) to attain a value equal to Delta H. We propose that the calculated time interval t represents the waiting time at the field H required for viscosity effects to bring about the equivalent change in magnetisation. If the working point of a permanent magnet or magnetic recording medium is known, this technique provides a quantitative estimate of the long-term stability of the magnetic state of the material.

U2 - 10.1016/S0304-8853(97)00055-3

DO - 10.1016/S0304-8853(97)00055-3

M3 - Article

VL - 171

SP - 163

EP - 169

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

ER -