“Pair Correlations in Superconducting-Magnetic Heterostructures“ by Andreas Bill (CSULB)

Date: 
Wednesday, May 31, 2017 - 4:00pm
Series: 
Condensed Matter Journal Club Seminar

Spin correlations of superconducting pairs leaking into a magnetic material are affected by magnetic inhomogeneities.  Using the tunable domain wall of an exchange spring we investigate pair correlation mixing and current reversal (0- π transitions) in wide Josephson junctions. Helical structures and multilayers of misaligned homogeneous ferromagnets are also considered.  Analyzing the Gor’kov functions we show that these heterostructures display qualitatively different mixtures of pair correlations due to the cascade effect [1].  We find that so-called short-range singlet correlations are present deep in the magnetic material [2].  The Josephson current can be tuned with the twisting of the domain wall, and the 0-π transition in the exchange spring is shown to result from the competition of singlet and triplet correlations. We propose to divide hybrid systems into two classes that involve discrete and continuous domain walls, respectively [3,4].  We also propose a classification of 0-π transitions into three types, according to the symmetry of pair correlations responsible for the current reversal [4].

 

Support from the National Science Foundation (DMR-1309341) is greatly appreciated.

 

  1. T.E. Baker, A. Richie-Halford, O.E. Icreverzi, and A. Bill, Europhys. Lett. 107, 17001 (2014).
  2. T.E. Baker, A. Richie-Halford, and A. Bill, New J. Phys. 16, 093048 (2014). See also the video abstract.
  3. T.E. Baker and A. Bill, AIP Advances, 6, 055811 (2016).
  4. .T.E. Baker, A. Richie-Halford, and A. Bill, Phys. Rev. B 94, 104518 (2016).
Location: 
PAB 4-330