{"id":28662,"date":"2023-12-12T10:49:29","date_gmt":"2023-12-12T05:19:29","guid":{"rendered":"https:\/\/iiser.ntc-us.com\/iisernew\/?p=28662"},"modified":"2023-12-12T10:49:29","modified_gmt":"2023-12-12T05:19:29","slug":"composite-fermions-and-fermi-surfaces","status":"publish","type":"post","link":"https:\/\/iiser.ntc-us.com\/iisernew\/composite-fermions-and-fermi-surfaces\/","title":{"rendered":"Composite fermions and Fermi surfaces"},"content":{"rendered":"

January 23<\/span>, 202<\/span>3<\/span>:<\/span><\/strong><\/span>\u00a0Prof.\u00a0<\/span>Ravindra Bhatt<\/span>,\u00a0<\/span>Princeton University<\/span><\/p>\n

Title<\/span><\/strong><\/span>:<\/strong><\/span>\u00a0<\/span>Composite fermions and Fermi surfaces<\/span><\/p>\n

 <\/p>\n

Abstract<\/span><\/strong><\/span>:<\/strong><\/span>\u00a0<\/span>The Nobel prize winning discoveries of the integer and fractional quantum Hall effects (IQHE\/FQHE) triggered intensive research on electrons in two dimensions in a strong perpendicular magnetic field. Detailed investigations uncovered a rich phase diagram of a seemingly very simple system and led to a comprehensive understanding of various phases, and exotic phenomena associated with them. These include charge fractionalization, Abelian and nonAbelian quantum states, topological spin excitations, and charge-density-wave phases, to name a few. This body of work paved the way for the new field of topological materials in the 21st century.<\/span><\/p>\n

 <\/p>\n

The composite fermion picture developed by Jain provides a natural way to understand the sequence of FQH phases. It also naturally predicts the existence of certain gapless phases at even denominator filling fractions of a Landau level in the midst of the more common gapped FQH phases with odd denominator filling fractions and quantized Hall conductance. In particular, the phase for a half-filled lowest Landau level (filling factor n = 1\/2) is seen as a Fermi liquid of composite fermions formed out of electrons bound to two vortices, in the absence of a magnetic field.<\/span><\/p>\n

 <\/p>\n

After briefly reviewing the arguments for various fractional quantum Hall phases following the picture of composite fermions, we concentrate on the gapless phase at filling factor n = 1\/2 and explore the nature of its Fermi surface. We will compare its behavior with that of Fermi surfaces of familiar metals with weak electron-electron interactions, which are known to depend sensitively on the electronic structure of the material. We ask questions such as – What is the relationship between the Fermi surface of electrons at zero magnetic field and the composite fermion Fermi surface? How sensitive is the latter to perturbations of the zero-field Hamiltonian? What happens when the system does not have rotational symmetry with a circular Fermi surface at zero magnetic field? Using a combination of analytic and numerical techniques, we show that the answer is both surprising and amenable to a parameter free experimental test, which it passes with surprising accuracy.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

January 23, 2023:\u00a0Prof.\u00a0Ravindra Bhatt,\u00a0Princeton University Title:\u00a0Composite fermions and Fermi surfaces   Abstract:\u00a0The Nobel prize winning discoveries of the integer and fractional quantum Hall effects (IQHE\/FQHE) triggered intensive research on electrons in two dimensions in a strong perpendicular magnetic field. Detailed investigations uncovered a rich phase diagram of a seemingly very simple system and led to… Continue reading Composite fermions and Fermi surfaces<\/span><\/a><\/p>\n","protected":false},"author":7,"featured_media":27885,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_expiration-date-status":"saved","_expiration-date":1702358220,"_expiration-date-type":"category","_expiration-date-categories":[],"_expiration-date-options":{"expireType":"category","id":28662}},"categories":[109],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/posts\/28662"}],"collection":[{"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/comments?post=28662"}],"version-history":[{"count":1,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/posts\/28662\/revisions"}],"predecessor-version":[{"id":28663,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/posts\/28662\/revisions\/28663"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/media\/27885"}],"wp:attachment":[{"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/media?parent=28662"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/categories?post=28662"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/iiser.ntc-us.com\/iisernew\/wp-json\/wp\/v2\/tags?post=28662"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}