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PRODID:UW-Madison-Physics-Events
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SEQUENCE:1
UID:UW-Physics-Event-9205
DTSTART:20250502T191500Z
DTEND:20250502T204500Z
DTSTAMP:20260413T151418Z
LAST-MODIFIED:20250425T152907Z
LOCATION:2104 CH
SUMMARY:Superconducting diode effect\, Thesis Defense\, Jaglul Hasan\,
  Physics PhD student
DESCRIPTION:In this thesis\, we explore the generalities of the superc
 urrent diode effect. As an illustrative example\, we examine a model o
 f a two-dimensional superconductor with Rashba-type spin-orbit couplin
 g under an in-plane magnetic field and in the clean limit\, which real
 izes a helical phase. First\, we utilize Ginzburg-Landau phenomenology
  to derive a general formula for the diode efficiency. This is achieve
 d by incorporating higher gradient terms in the Lifshitz invariants\, 
 which are responsible for the nonreciprocal superflow. Subsequently\, 
 we validate these results through microscopic diagrammatic computation
  and further estimate correction terms arising from interband pairing 
 correlations. We provide a detailed comparison to prior investigations
  of this problem conducted within the framework of the quasiclassical 
 approximation based on the Eilenberger equation.<br>
\n<br>
\nEven tho
 ugh superconducting diode effect (SDE) has garnered significant attent
 ion due to its potential applications in superconducting electronics\,
  the role of disorder scattering in SDE has rarely been considered\, d
 espite its potential qualitative impact\, as we demonstrate. We invest
 igate SDE in a disordered Rashba superconductor under an in-plane magn
 etic field\, employing a self-consistent Born approximation to derive 
 the corresponding Ginzburg-Landau theory. Our analysis reveals two sur
 prising effects. First\, in the strong Rashba SOC regime\, disorder be
 comes the driving mechanism of SDE\, which vanishes in its absence. In
  this case\, we show that disorder-induced mixing of singlet and tripl
 et superconducting orders underlies the effect. Second\, in the weak R
 ashba spin-orbit coupling (SOC) regime\, disorder can reverse the dire
 ction of the diode effect\, indicated by a sign change in the supercon
 ducting diode efficiency coefficient.
URL:https://www.physics.wisc.edu/events/?id=9205
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