A Study of Reversible and Irreversible Magnetization Behaviour in Conventional Superconductors
Field-cooled (FC) and zero field-cooled (ZFC) magnetization curves in a constant dc field H were measured as a function of temperature. The temperature at which these merge [T r (H)] gives a point on the irreversibility line.
Hysteretic isothermal magnetizaton, i.e, M vs H, curves were measured where M is the sample’s magnetization per unit volume and H is the applied field. The field, [H r (T)], at which the hysteresis vanishes gives a point on the (T r , H r ) line.
The complex ac magnetic susceptibility (χ = χ′ H + iχ″ H ) was measured in constant dc field H as a function of temperature. A thermoaynamic response requires that χ′ H (T) be positive just below T c and this is called the Differential Paramagnetic Effect (DPE).2 The temperature at which χ′ H (T) switches from positive to negative is identified with T r (H).
From the simultaneous measurements of χ″ H (T) as a function of temperature in a constant dc field, the temperature at which it peaks is identified as T p (H).
KeywordsHysteresis Loss Perpendicular Orientation Disc Plane Irreversibility Line Conventional Superconductor
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