korean english


Home > 게시판 > 세미나

○ Date : 2015년 11월 13일(금) 오후 4:00
○ Place :  기초학문관 3층 창조존

○ Speaker : 이  현  정  박사님 (KAIST)
○ Topic : Kondo screening in mixed valence and heavy fermion compounds and the signatures of Nozieres’ exhaustion

○ Abstract: 

Whereas most rare-earth compounds with the stable valence show concomitant local magnetic moments which order magnetically at low temperature, the mixed-valence compounds have avoided local magnetism of the rare earths through the hybridization process between the degenerate valence states. To understand the relation of this hybridization with the Kondo effect, it is necessary to have a low energy Hamiltonian for the lattice problem with which one can answer questions like what determines the coherence scale in the Kondo problem and answer questions such as the exhaustion paradox raised by P. Nozieres [Ann. Phys. (Paris) 10, 19, (1985)].

To investigate the exhaustion problem in Kondo lattices, we examine the dynamical properties of the periodic Anderson model such as the local spectral density and the spin excitation spectrum within the dynamical mean-field theory using the numerical renormalization-group technique. Pursuing the high impurity-concentration and the strong coupling limit simultaneously, we find a transition between coherent and incoherent Kondo regime, characterized by closing of the hybridization gap and appearance of Fano resonance. The appearance of the Fano resonance is attributed to coherent valence fluctuation which leads to a polaron like depression of the density of states near the van Hove singularity in the conduction band. We discuss the competing mechanism between the two screening channels, i.e. spin and valence fluctuations, and the relevance to the quantum criticality exhibited in Yb based heavy fermion superconductors.

번호 제목 날짜 조회 수
공지 <12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생 2016.11.28 1090031
637 <Mar.17(Wed.)> Glue spectrum for superconductivity obtained via optical spectroscopy 2021.03.10 30770
636 <Mar.10(Wed.)> Dark matter searches in neutrino detectors 2021.03.04 56748
635 <Mar.3(Wed.)>Scaling laws in Natural Language Processing 2021.02.25 371856
634 <Feb.18(Thu.)> Hund's metallicity in the vicinity of a Van Hove singularity / Correlated topological phases in strongly correlated heterostructures 2021.02.16 201326
633 <Jan.28(Thu.)>X-ray Absorption Spectroscopy Study of Amorphous Oxide Thin Films 2021.01.27 113676
632 2021학년도 1학기 콜로퀴움 일정 2021.01.13 146242
631 <Jan.14(Thu.)>Oxygen sponge effects for epitaxial manganite thin film design 2021.01.11 248313
630 <Dec.9(Wed.)>한국형 암흑물질 실험 2020.12.02 16272
629 <Dec.2(Wed.)>The era of gravitational waves, and the science that makes it possible 2020.11.25 42262
628 <Nov.18(Wed.)>When Physics meets the Living Cells 2020.11.11 107195
627 <Nov.11(Wed.)>Nonlinear optics to study charge, spin, and crystalline structures 2020.11.04 32331
626 <Nov.4(Wed.)>Progresses in Elucidating the Optoelectronic Properties of Perovskite Semiconductor 2020.10.28 83760
625 <11/5(Thu.)> Higher Spin Cooper Pairs 2020.10.27 116652
624 <Oct.28(Wed.)> Physics of Global Warming 2020.10.22 43286
623 <Oct.14(Wed.)>New Ways to Search for the Dark World 2020.10.12 16605
622 <Oct.7(Wed.)>Organic Photodiode for Image Sensor 2020.09.24 66266
621 <Sep.23(Wed.)>나는 내 마음이야 2020.09.16 17544
620 <Sep.16(Wed.)>Artificial Crystal 2020.09.14 20433
619 <8/1(Sat.)> Recent Advances in Deep Learning 2020.07.29 37768
618 2020학년도 2학기 콜로퀴움 일정 2020.07.16 168955