Patent ID: 7339764

Claim:
A method of designing a patterned magnetic recording medium comprising a magnetic film with perpendicular magnetic anisotropy which is patterned into dots, comprising steps of: setting values to dot pattern periods P x and P y in an x-direction and in an y-direction, a thickness “t”, a thermal stability factor K n , a minimum inter-dot spacing S 0 , and a maximum recording field H m ; setting an initial value to a saturation magnetization M s ; finding a dot size “a” in the x-direction and a nucleation field for magnetization reversal H n in accordance with the formulas given below: a=P x −S 0, H n =2 K n *k B T /( a 2 *M s *γ*t ), where k B is the Boltzmann constant, T is an absolute temperature, and γ is a ratio of the dot size in the y-direction to the dot size in the x-direction; finding an inclination α of a perpendicular M-H loop of the magnetic dot with a shape of (a, γa, t) in accordance with the formula given below: α=4π/( N d +ΔH c /M s ), where N d is a perpendicular demagnetizing factor of the magnetic dot, and ΔH c is a distribution broadening of a coercivity H c in the patterned magnetic recording medium, and estimating the coercivity H c =H n +(4 πM s /α) and a saturation field H s =H n +(8 πM s /α); and judging whether the saturation field H s is lower than the maximum recording field H m , and, if the saturation field H s is not lower than the maximum recording field H m , increasing the value of the saturation field M s and repeating the steps given above, thereby determining the dot pattern periods P x and P y in the x-direction and in the y-direction required for achieving a desired recording density, the thickness “t”, the thermal stability factor K n , the minimum inter-dot spacing S 0 , and magnetic properties of M s , H n and H c satisfying the condition of the maximum recording field H m .