TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.15.3.110
TI  - Electron addition spectral functions of low-density polaron liquids
PY  - 2023/09/22
UR  - https://scipost.org/SciPostPhys.15.3.110
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 15
IS  - 3
SP  - 110
A1  - Nocera, Alberto
AU  - Berciu, Mona
AB  - Spectral functions are important quantities that contain a wealth of information about the quasiparticles of a system, and that can also be measured experimentally. For systems with electron-phonon coupling, good approximations for the spectral function are available only in the Migdal limit (at Fermi energies much larger than the typical phonon frequency, $E_F\gg \Omega$, requiring a large carrier concentration $x$) and in the single polaron limit (at $x=0$). Here we show that the region with $x\ll 1$ ($E_F <\Omega$) can also be reliably investigated with the Momentum Average (MA) variational approximation, which essentially describes the formation of a polaron above an inert Fermi sea. Specifically, we show that for the one-dimensional spinless Holstein model, the MA spectral functions compare favorably with those calculated using variationally exact density matrix renormalization group simulations (DMRG) evaluated directly in frequency-space, so long as $x<0.1$ and the adiabaticity ratio $\Omega/t>0.5$. Unlike in the Migdal limit, here 'polaronic physics' emerges already at moderate couplings. The relevance of these results for a spinful low-$x$ metal is also discussed.
ER  -

@Article{10.21468/SciPostPhys.15.3.110,
	title={{Electron addition spectral functions of low-density polaron liquids}},
	author={Alberto Nocera and Mona Berciu},
	journal={SciPost Phys.},
	volume={15},
	pages={110},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.15.3.110},
	url={https://scipost.org/10.21468/SciPostPhys.15.3.110},
}