{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/62867"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/62867","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Competition and unification of Kondo coherence and magnetic ordering","abstract":"The heavy fermion quantum critical point is one of the most puzzling problems in the field of highly correlated electrons. This is a quantum critical point separating a non-magnetic heavy fermi liquid metal from an antiferromagnetically ordered metal. The major problem facing us is the fact that, based on new experiments, these two phases seem to collapse simultaneously at the quantum critical point, giving rise to a drastic change in the fermi surface across the transition. In the quest for a toy model to envision this simultaneous collapse, we study the Kondo-Heisenberg model on the honeycomb lattice at half-filling. We study a fixed point controlling the quantum phase transition of a Kondo coherent phase to a critical phase called algebraic spin liquid. Studying such a fixed point has been proposed to be key to understanding the quantum critical point in heavy fermions. The relativistic structure of the lowenergy theory is the hallmark of our theory. The critical theory, however, can only be managed by extending the spin flavors well beyond the physical up and down, a technique known as the \"large-N expansion\". We later approach the physical case of SU(2) spins head-on and propose a novel idea to unify the distinct Kondo coherent phase and antiferromagnetic phase. We propose destroying the Kondo phase by proliferating Kondo vortices. We show that spin-triplets can be created by a Kondo vortex because of the zero modes it generates at the chemical potential. This gives us a nice picture that a magnetic transition can be driven by proliferating Kondo vortices. We also identify a class of these spin-triplets that transform like a Néel order. Due to the half-filled limitation of this model, however, this Kondo-vortexdriven antiferromagentic transition is in the O(3) universality class. We also prove that, starting from the pure Kondo lattice model, due to the charge-conjugation symmetry, antiferromagentic Heisenberg exchange will be generated, and the pure Kondo lattice model transforms to the Kondo-Heisenberg model we have studied. A major asset of the model we have studied is that it can be simulated using a signfree quantum Monte Carlo method, and our analytical results can all be probed in numerics. We present our preliminary numerical results for this model.","abstract_html":"The heavy fermion quantum critical point is one of the most puzzling problems in the field of highly correlated electrons. This is a quantum critical point separating a non-magnetic heavy fermi liquid metal from an antiferromagnetically ordered metal. The major problem facing us is the fact that, based on new experiments, these two phases seem to collapse simultaneously at the quantum critical point, giving rise to a drastic change in the fermi surface across the transition. In the quest for a toy model to envision this simultaneous collapse, we study the Kondo-Heisenberg model on the honeycomb lattice at half-filling. We study a fixed point controlling the quantum phase transition of a Kondo coherent phase to a critical phase called algebraic spin liquid. Studying such a fixed point has been proposed to be key to understanding the quantum critical point in heavy fermions. The relativistic structure of the lowenergy theory is the hallmark of our theory. The critical theory, however, can only be managed by extending the spin flavors well beyond the physical up and down, a technique known as the "large-N expansion". We later approach the physical case of SU(2) spins head-on and propose a novel idea to unify the distinct Kondo coherent phase and antiferromagnetic phase. We propose destroying the Kondo phase by proliferating Kondo vortices. We show that spin-triplets can be created by a Kondo vortex because of the zero modes it generates at the chemical potential. This gives us a nice picture that a magnetic transition can be driven by proliferating Kondo vortices. We also identify a class of these spin-triplets that transform like a Néel order. Due to the half-filled limitation of this model, however, this Kondo-vortexdriven antiferromagentic transition is in the O(3) universality class. We also prove that, starting from the pure Kondo lattice model, due to the charge-conjugation symmetry, antiferromagentic Heisenberg exchange will be generated, and the pure Kondo lattice model transforms to the Kondo-Heisenberg model we have studied. A major asset of the model we have studied is that it can be simulated using a signfree quantum Monte Carlo method, and our analytical results can all be probed in numerics. We present our preliminary numerical results for this model.","abstract_has_math":false,"creators":["Saremi, Saeed"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Physics.","school":null,"contributors":[],"advisors":["Patrick A. Lee."],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009","date_published":"2009","updated_at":"2026-07-22T22:21:17Z","subjects":["Physics."],"languages":["eng"],"rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/62867","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Patrick A. Lee."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. Dept. of Physics."]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Massachusetts Institute of Technology. Dept. of Physics."]},{"key":"dc:creator","label":"Author","values":["Saremi, Saeed"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2011-05-23T15:29:14Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2011-05-23T15:29:14Z"]},{"key":"dc:date.issued","label":"Date","values":["2009"]},{"key":"dc:publisher","label":"Institution","values":["Massachusetts Institute of Technology"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1721.1/62867"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.","This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.","Cataloged from student submitted PDF version of thesis.","Includes bibliographical references (p. 105-108)."]},{"key":"dc:description.abstract","label":"Abstract","values":["The heavy fermion quantum critical point is one of the most puzzling problems in the field of highly correlated electrons. This is a quantum critical point separating a non-magnetic heavy fermi liquid metal from an antiferromagnetically ordered metal. The major problem facing us is the fact that, based on new experiments, these two phases seem to collapse simultaneously at the quantum critical point, giving rise to a drastic change in the fermi surface across the transition. In the quest for a toy model to envision this simultaneous collapse, we study the Kondo-Heisenberg model on the honeycomb lattice at half-filling. We study a fixed point controlling the quantum phase transition of a Kondo coherent phase to a critical phase called algebraic spin liquid. Studying such a fixed point has been proposed to be key to understanding the quantum critical point in heavy fermions. The relativistic structure of the lowenergy theory is the hallmark of our theory. The critical theory, however, can only be managed by extending the spin flavors well beyond the physical up and down, a technique known as the \"large-N expansion\". We later approach the physical case of SU(2) spins head-on and propose a novel idea to unify the distinct Kondo coherent phase and antiferromagnetic phase. We propose destroying the Kondo phase by proliferating Kondo vortices. We show that spin-triplets can be created by a Kondo vortex because of the zero modes it generates at the chemical potential. This gives us a nice picture that a magnetic transition can be driven by proliferating Kondo vortices. We also identify a class of these spin-triplets that transform like a Néel order. Due to the half-filled limitation of this model, however, this Kondo-vortexdriven antiferromagentic transition is in the O(3) universality class. We also prove that, starting from the pure Kondo lattice model, due to the charge-conjugation symmetry, antiferromagentic Heisenberg exchange will be generated, and the pure Kondo lattice model transforms to the Kondo-Heisenberg model we have studied. A major asset of the model we have studied is that it can be simulated using a signfree quantum Monte Carlo method, and our analytical results can all be probed in numerics. We present our preliminary numerical results for this model."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Competition and unification of Kondo coherence and magnetic ordering"]}]}],"canonical_facts":{"dc:contributor.advisor":["Patrick A. Lee."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Physics."],"dc:contributor.other":["Massachusetts Institute of Technology. Dept. of Physics."],"dc:creator":["Saremi, Saeed"],"dc:date.accessioned":["2011-05-23T15:29:14Z"],"dc:date.available":["2011-05-23T15:29:14Z"],"dc:date.issued":["2009"],"dc:description":["Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.","This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.","Cataloged from student submitted PDF version of thesis.","Includes bibliographical references (p. 105-108)."],"dc:description.abstract":["The heavy fermion quantum critical point is one of the most puzzling problems in the field of highly correlated electrons. This is a quantum critical point separating a non-magnetic heavy fermi liquid metal from an antiferromagnetically ordered metal. The major problem facing us is the fact that, based on new experiments, these two phases seem to collapse simultaneously at the quantum critical point, giving rise to a drastic change in the fermi surface across the transition. In the quest for a toy model to envision this simultaneous collapse, we study the Kondo-Heisenberg model on the honeycomb lattice at half-filling. We study a fixed point controlling the quantum phase transition of a Kondo coherent phase to a critical phase called algebraic spin liquid. Studying such a fixed point has been proposed to be key to understanding the quantum critical point in heavy fermions. The relativistic structure of the lowenergy theory is the hallmark of our theory. The critical theory, however, can only be managed by extending the spin flavors well beyond the physical up and down, a technique known as the \"large-N expansion\". We later approach the physical case of SU(2) spins head-on and propose a novel idea to unify the distinct Kondo coherent phase and antiferromagnetic phase. We propose destroying the Kondo phase by proliferating Kondo vortices. We show that spin-triplets can be created by a Kondo vortex because of the zero modes it generates at the chemical potential. This gives us a nice picture that a magnetic transition can be driven by proliferating Kondo vortices. We also identify a class of these spin-triplets that transform like a Néel order. Due to the half-filled limitation of this model, however, this Kondo-vortexdriven antiferromagentic transition is in the O(3) universality class. We also prove that, starting from the pure Kondo lattice model, due to the charge-conjugation symmetry, antiferromagentic Heisenberg exchange will be generated, and the pure Kondo lattice model transforms to the Kondo-Heisenberg model we have studied. A major asset of the model we have studied is that it can be simulated using a signfree quantum Monte Carlo method, and our analytical results can all be probed in numerics. We present our preliminary numerical results for this model."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["http://hdl.handle.net/1721.1/62867"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Physics."],"dc:title":["Competition and unification of Kondo coherence and magnetic ordering"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:21:17Z"}