Ferromagnetic exchange field stabilized antiferromagnetic ordering in a cuprate superconductor

Biswajit Dutta; A. Banerjee

doi:10.1103/PhysRevB.106.134520

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Ferromagnetic exchange field stabilized antiferromagnetic ordering in a cuprate superconductor

Biswajit Dutta, A. Banerjee

DOI 10.1103/PhysRevB.106.134520 · Physical Review B

T1

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Abstract

We report experimental evidence of the formation of antiferromagnetic clusters well within cuprate superconductor La1.85Sr0.15CuO4 (LCu) in a composite made of LCu and ferromagnet La0.6Sr0.4CoO3 (LCo). It is found that the exchange field of LCo suppresses the dynamic antiferromagnetic spin fluctuation of LCu and short-range-ordered superparamagnetic type antiferromagnetic (AFM) clusters are formed at the cost of superconducting volume fraction. With the help of linear and nonlinear ac-susceptibility measurements, we show evidence of thermal blocking of these antiferromagnetic clusters. Further, we show that the shrank superconducting volume fractions undergo the quantum size effect (QSE) and follow DeGennes-Tinkham theory on the finite size effect of a superconductor. These give a clear indication that the antiferromagnetic spin fluctuation can be a mediator of electron pairing in cuprate superconductors.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
La1.85Sr0.15CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown