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SUMMARY:Magnetic-field Induced Pair Density Wave State in the Cuprate Vort
 ex Halo - Dr. Stephen Edkins\, Stanford
DTSTART:20180502T100000Z
DTEND:20180502T113000Z
UID:TALK103876@talks.cam.ac.uk
CONTACT:Malte Grosche
DESCRIPTION:When very high magnetic fields suppress the superconductivity 
 in underdoped cuprates\, an exceptional new electronic phase appears. It s
 upports remarkable and unexplained quantum oscillations and exhibits an un
 identified density wave (DW) state. Although generally referred to as a "c
 harge" density wave (CDW) because of the observed charge density modulatio
 ns\, theory indicates that this could actually be the far more elusive ele
 ctron-pair density wave state (PDW). To search for evidence of a field-ind
 uced PDW in cuprates\, we visualize the modulations in the density of elec
 tronic states N(r) within the halo surrounding Bi2Sr2CaCu2O8 vortex cores.
  This reveals multiple signatures of a field-induced PDW\, including two s
 ets of N(r)modulations occurring at wavevectors QP and 2QP\, both having p
 redominantly s-symmetry form factors\, the amplitude of the latter decayin
 g twice as rapidly as the former\, along with induced energy-gap modulatio
 ns at QP . Such a microscopic phenomenology is in detailed agreement with 
 theory for a field-induced primary PDW that generates secondary CDWs withi
 n the vortex halo. These data indicate that the fundamental state generate
 d by increasing magnetic fields from the underdoped cuprate superconductin
 g phase is actually a PDW with approximately eight CuO2 unit-cell periodic
 ity (λ=8a0) and predominantly d-symmetry form factor.
LOCATION:Mott Seminar Room (531)\, Cavendish Laboratory\, Department of Ph
 ysics
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