Magnetic Penetration Depth of UBe₁₃ and UPt₃ Derived by DC Magnetization Measurements

Abstract

DC magnetization of heavy-fermion superconductors UBe 13 and UPt 3 has been measured, and the magnetic penetration depth change ∆λ(T) = λ(T) − λ(T min), where T min is the lowest temperature, is derived. For UBe 13 , a single crystal and a polycrystal show a similar temperature dependence of ∆λ(T) that follows a T 2 law in the limited low-temperature range. When UPt 3 is measured under high pressure, a linear temperature dependence of ∆λ(T) is observed both below and above P c ∼ 0.4 GPa, above which an antiferromagnetic correlation disappears, while the increase rate above P c is about twice as large as that below P c , suggesting that the superconducting phase is modified above P c .