We consider a two-dimensional electron system with Coulomb interaction between particles at a finite temperature $T$ . We show that the dynamic Kohn anomaly in the response function at $2{k}_{F}$ leads to a nonanalytic, linear-in- $T$ correction to the spin susceptibility, $\ensuremath{\delta}\ensuremath{\chi}(T)=aT$, the same as in systems with short-range interaction. We show that the singularity of the Coulomb interaction at $q=0$ does not invalidate the expansion of the prefactor $a$ in powers of ${r}_{s}$ , but makes the expansion nonanalytic.We consider a two-dimensional electron system with Coulomb interaction between particles at a finite temperature $T$. We show that the dynamic Kohn anomaly in the response function at $2{k}_{F}$ leads to a nonanalytic, linear-in-$T$ correction to the spin susceptibility, $\ensuremath{\delta}\ensuremath{\chi}(T)=aT$, the same as in systems with short-range interaction. We show that the singularity of the Coulomb interaction at $q=0$ does not invalidate the expansion of the prefactor $a$ in powers of ${r}_{s}$, but makes the expansion nonanalytic.

arXiv:cond-mat/0501132Physical Review BMay 11, 200520 citations

Spin susceptibility of a many electron system

A. R. P. Rau, A. K. Rajagopal

Physica B+CJan 1, 19770 citations

Dynamic spin susceptibility in the Hubbard model

V. A. Moskalenko, Nikolay M. Plakida

Theoretical and Mathematical PhysicsOct 1, 19975 citations

Dynamical spin susceptibility and magnetic ordering in a square-octagon lattice in the Hubbard model

Mona Abdi, Bandar Astinchap, Erfan Norian

In this work, we investigate the electronic and magnetic properties of the two-dimensional square-octagon structure (2DSOS) using a tight-binding framework augmented by on-site Coulomb interaction. We examine how varying hopping parameters, magnetic flux, and interaction strength influence the system’s band structure, dynamical transverse spin susceptibility (DTSS), and static spin structure factor (SSSF). Our findings reveal the emergence of a flat band when the third-nearest-neighbor hopping term t 3 equals the nearest-neighbor hopping t 1 , significantly affecting the magnetic response. The frequency dependence of the DTSS demonstrates that both magnetic flux and Coulomb repulsion shift the resonance peaks to higher frequencies and suppress their intensities, indicating a suppression of low-energy spin fluctuations. Moreover, the temperature dependence of the SSSF underlines a transition from paramagnetic to ferromagnetic behavior as the ratio t 2 /t 1 increases. These results highlight the crucial role of electronic correlations and lattice geometry in shaping the spin dynamics of flat-band systems and offer valuable insights for designing future spintronic and correlated electron devices.In this work, we investigate the electronic and magnetic properties of the two-dimensional square-octagon structure (2DSOS) using a tight-binding framework augmented by on-site Coulomb interaction. We examine how varying hopping parameters, magnetic flux, and interaction strength influence the system’s band structure, dynamical transverse spin susceptibility (DTSS), and static spin structure factor (SSSF). Our findings reveal the emergence of a flat band when the third-nearest-neighbor hopping term t 3 equals the nearest-neighbor hopping t 1 , significantly affecting the magnetic response. The frequency dependence of the DTSS demonstrates that both magnetic flux and Coulomb repulsion shift the resonance peaks to higher frequencies and suppress their intensities, indicating a suppression of low-energy spin fluctuations. Moreover, the temperature dependence of the SSSF underlines a transition from paramagnetic to ferromagnetic behavior as the ratio t 2 /t 1 increases. These results highlight the crucial role of electronic correlations and lattice geometry in shaping the spin dynamics of flat-band systems and offer valuable insights for designing future spintronic and correlated electron devices.

Scientific ReportsDec 8, 20250 citations

Spin Susceptibility of an Interacting Electron Gas

Harjinder Singh, K. N. Pathak

A simple calculation of the wave-vector- and frequency-dependent paramagnetic spin susceptibility of an interacting electron gas is presented. The equation of motion of the double-time Green's function is solved using a moment-conserving decoupling approximation. For the short-range interaction, our expression for the dynamic spin susceptibility reduces to a previous result of Wolff. In the static and long-wavelength limit, our result for the Stonerenhanced spin susceptibility coincides with that obtained from consideration of the groundstate energy in the Hartree-Fock approximation.A simple calculation of the wave-vector- and frequency-dependent paramagnetic spin susceptibility of an interacting electron gas is presented. The equation of motion of the double-time Green's function is solved using a moment-conserving decoupling approximation. For the short-range interaction, our expression for the dynamic spin susceptibility reduces to a previous result of Wolff. In the static and long-wavelength limit, our result for the Stonerenhanced spin susceptibility coincides with that obtained from consideration of the groundstate energy in the Hartree-Fock approximation.

Physical review. B, Solid stateOct 15, 19726 citations

We consider a two-dimensional electron system with Coulomb interaction between particles at a finite temperature

T

. We show that the dynamic Kohn anomaly in the response function at

2{k}_{F}

leads to a nonanalytic, linear-in-

T

correction to the spin susceptibility, $\ensuremath{\delta}\ensuremath{\chi}(T)=aT$, the same as in systems with short-range interaction. We show that the singularity of the Coulomb interaction at

q=0

does not invalidate the expansion of the prefactor

a

in powers of

{r}_{s}

, but makes the expansion nonanalytic.