Patent ID: 6894857

Claim:
A magnetic recording apparatus, comprising: a magnetic recording medium having a magnetic recording layer, the medium being required to have a stable retention time tat for recorded magnetization at room temperature and having a thermal-fluctuation stability coefficient β st at room temperature calculated from a thermal-fluctuation stability coefficient β(T) at an absolute temperature T, expressed by the following equation: β( T )= K u V/k B T, where K u is a magnetic anisotropy energy density, V is an activation volume, and k B is Boltzmann's constant, and the medium showing an equivalent degradation time t EQ calculated from the following equation: t EQ =Σ(Δt EQ ), that sums values of Δt EQ within a given period of time Δt for a time span during which the medium is kept at a temperature at which the recorded magnetization is substantially degraded, where Δt EQ is defined by the following equation: Δ t EQ =exp(ln(Δt)−β+β st ), where β is a thermal-fluctuation stability coefficient for a medium temperature T in the period of time Δt, wherein the relationship of t EQ <t st is met between the stable retention time t st for recorded magnetization at room temperature and the equivalent degradation time t EQ ; a heater configured to heat the medium; and a magnetic head configured to apply a magnetic field to the medium.