Lifshitz Transitions in Magnetic Phases of the Periodic Anderson Model

Abstract

We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with a finite Coulomb interaction between f electrons. We apply the variational Monte Carlo method to the model by using the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge-density-wave states. We find that an antiferromagnetic phase is realized around half-filling and a ferromagnetic phase is realized when the system is far away from half-filling. In both magnetic phases, Lifshitz transitions take place. By analyzing the electronic states, we conclude that the Lifshitz transitions to large ordered-moment states can be regarded as itinerant-localized transitions of the f electrons.

Ferromagnetism in the Kondo-lattice

“…It was found previously [47,48] that for the antiferromagnetic phases, bond fermion theory agrees well with numerical results for the 2D KLM. More precisely, the quite intricate phase diagram in the (J/t, n c ) plane obtained from bond Fermion theory agrees qualitatively with that from VMC [26,27,29] and DMFT [30], the quasiparticle band structure for the antiferromagnetic phase of the Kondo insulator -i.e. the KLM for n e = 2 -and its change with J agree in considerable detail with that from DCA [32].…”

“…The KLM has been discussed frequently by using the mean-field (or saddle-point) approximation, where the exchange term which is quartic in electron operators is mean-field factorized [7][8][9][10][11][12][13][14][15][16][17]. There have also been many numerical studies using density matrix renormalization group calculations [18][19][20][21][22], quantum Monte-Carlo [23], series expansion [24,25] variational Monte-Carlo (VMC) [26][27][28][29] Dynamical Mean Field Theory (DMFT) [30] or Dynamical Cluster Approximation (DCA) [31,32].…”

“…These materials have received considerable attention due to the coexistence of superconductivity and ferromagnetism [35]. Ferromagnetism in the KLM or PAM was studied in the mean-field approximation [36], the Gutzwiller wave function [37][38][39][40], VMC [28,29], DMFT [41][42][43] and DCA [43]. In the present manuscript we want to explore the possibility of ferromagnetic ordering in the KLM by using bond fermion theory [44][45][46].…”

Variational Wavefunction for the Periodic Anderson Model with Onsite Correlation Factors

“…The above theories assumed the paramagnetic (PM) state; however, within the GWF, it has also been revealed that the PM state is unstable against magnetic order in the parameter region where the heavy-fermion state is realized. 1,3,[5][6][7][8][9][10][11] To overcome this difficulty, we should improve the variational wavefunction. For this purpose, it is useful to consult the literature on other multiorbital systems since the periodic Anderson model is also a multiorbital system with the conduction band and f orbital.…”

“…One is the GWF, which has been used to study this model, for example, by the variational Monte Carlo method as in this study. 2,8,9,11 For U → ∞, the Gutzwiller parameter is zero, and the GWF is given by…”