Zobrazeno 1 - 10
of 663
pro vyhledávání: '"KOPIETZ, P."'
Publikováno v:
Phys. Rev. B 110, 144416 (2024)
We show that the high-temperature expansion of the free energy and arbitrary imaginary-time-ordered connected correlation functions of quantum spin systems can be recursively obtained from the exact renormalization group flow equation for the generat
Externí odkaz:
http://arxiv.org/abs/2406.06270
Publikováno v:
Phys. Rev. B 109, 184410 (2024)
We use the spin functional renormalization group to investigate the $J_1$-$J_2$ quantum Heisenberg model on a square lattice. By incorporating sum rules associated with the fixed length of the spin operators as well as the nontrivial quantum dynamics
Externí odkaz:
http://arxiv.org/abs/2403.08713
Publikováno v:
Phys. Rev. B 109, 155101 (2024)
Using a functional renormalization group approach we derive the renormalization group (RG) flow of a dissipative variant of the Yukawa-Sachdev-Ye-Kitaev model describing $N$ fermions on a quantum dot which interact via a disorder-induced Yukawa coupl
Externí odkaz:
http://arxiv.org/abs/2312.14026
Publikováno v:
Phys. Rev. B 108, 115104 (2023)
Exact functional renormalization group (FRG) flow equations for quantum systems can be derived directly within an operator formalism without using functional integrals. This simple insight opens new possibilities for applying FRG methods to models fo
Externí odkaz:
http://arxiv.org/abs/2305.06928
Autor:
Hansen, Max O., Palan, Yash, Hahn, Viktor, Thomson, Mark D., Warawa, Konstantin, Roskos, Hartmut G., Demsar, Jure, Pientka, Falko, Tsyplyatyev, Oleksandr, Kopietz, Peter
Publikováno v:
Phys. Rev. B 108, 045148 (2023)
We re-examine the effect of long-range Coulomb interactions on the collective amplitude and phase modes in the incommensurate charge-density-wave ground state of quasi-one-dimensional conductors. Using an effective action approach we show that the lo
Externí odkaz:
http://arxiv.org/abs/2303.08580
Autor:
Tarasevych, Dmytro, Rückriegel, Andreas, Keupert, Savio, Mitsiioannou, Vasilios, Kopietz, Peter
Publikováno v:
Phys. Rev. B 106, 174412 (2022)
We use our recently developed functional renormalization group (FRG) approach for quantum spin systems to investigate the phase diagram of the frustrated $J_{1}J_{2}J_{3}$ quantum Heisenberg model on a cubic lattice. From a simple truncation of the h
Externí odkaz:
http://arxiv.org/abs/2208.05741
Publikováno v:
Phys. Rev. B 105, 224406 (2022)
We investigate dimerized quantum spin systems using the spin functional renormalization group approach proposed by Krieg and Kopietz [Phys. Rev. B 99, 060403(R) (2019)] which directly focuses on the physical spin correlation functions and avoids the
Externí odkaz:
http://arxiv.org/abs/2204.04074
Publikováno v:
Phys. Rev. B 105, 205148 (2022)
The Holstein model with dispersionless Einstein phonons is one of the simplest models describing electron-phonon interactions in condensed matter. A naive extrapolation of perturbation theory in powers of the relevant dimensionless electron-phonon co
Externí odkaz:
http://arxiv.org/abs/2203.08641
Autor:
Hahn, Viktor, Frey, Pascal, Serga, Alexander A., Vasyuchka, Vitaliy I., Hillebrands, Burkard, Kopietz, Peter, Rückriegel, Andreas
Publikováno v:
Phys. Rev. B 105 (2022) 144421
We derive and solve quantum kinetic equations describing the accumulation of magnetoelastic bosons in an overpopulated magnon gas realized in a thin film of the magnetic insulator yttrium iron garnet. We show that in the presence of a magnon condensa
Externí odkaz:
http://arxiv.org/abs/2112.03310
Autor:
Tarasevych, Dmytro, Kopietz, Peter
Publikováno v:
Phys. Rev. B 105, 024403 (2022)
We calculate the dynamic structure factor $S (\boldsymbol{k},\omega)$ in the paramagnetic regime of quantum Heisenberg ferromagnets for temperatures $T$ close to the critical temperature $T_c$ using our recently developed functional renormalization g
Externí odkaz:
http://arxiv.org/abs/2111.07621