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SUMMARY:“Old and new physics in the J1-J2 Heisenberg spin chain” - Pro
 f. Chris Hooley (Coventry)
DTSTART:20250605T130000Z
DTEND:20250605T143000Z
UID:TALK227980@talks.cam.ac.uk
CONTACT:Bo Peng
DESCRIPTION:In this talk\, I will briefly describe two of our recent piece
 s of work on the physics of the J1-J2 Heisenberg spin chain\, a one-dimens
 ional array of quantum spins coupled by first- and second-neighbour exchan
 ge interactions.  The first piece of work [1] concerns the case where J1 a
 nd J2 are both antiferromagnetic: in this case there is a phase transition
  from a Luttinger liquid to a valence bond solid as J2/J1 is increased\, a
 nd we provide a novel direct method to derive the field theory that descri
 bes the critical point between these two phases.  The second piece [2] con
 cerns the case where J1 is antiferromagnetic but J2 is strongly ferromagne
 tic: counter-intuitively\, there is a transition in this case as well\, bu
 t this time of a ‘liquid-to-liquid’ type.  We present a field-theory d
 escription of it\, and an analogue system of three coupled chains that hel
 ps to illustrate the physics.\n\n\n[1] F. Azad\, A. J. McRoberts\, CAH\, a
 nd A. G. Green\, “Generalized Haldane map from the matrix product state 
 path integral to the critical theory of the J1-J2 chain\,” Phys. Rev. Re
 search 7\, L012037 (2025).\n\n[2] A. J. McRoberts\, CAH\, and A. G. Green\
 , “Transition between critical antiferromagnetic phases in the J1-J2 spi
 n chain\,” arXiv:2411.08095v2 (2025).
LOCATION:Seminar Room 3\, RDC
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