Spin response and collective modes in simple metal dichalcogenides

Mukherjee, Dibya Kanti; Kundu, Arijit; Fertig, H. A.

doi:10.1103/physrevb.98.184413

Cited by 9 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Effects of electron-electron interactions in TMDs were considered previously in Refs. [17][18][19] The results predicted in Refs. 17,18 are valid if the exchange inter-valley (EIV) interaction is negligible.…”

Section: Introductionmentioning

confidence: 68%

See 1 more Smart Citation

Exchange intervalley scattering and magnetic phase diagram of transition metal dichalcogenide monolayers

2019

View full text Add to dashboard Cite

We analyze magnetic phases of monolayers of transition metal dichalcogenides that are two-valley materials with electron-electron interactions. The exchange inter-valley scattering makes two-valley systems less stable to the spin fluctuations but more stable to the valley fluctuations. We predict a first order ferromagnetic phase transition governed by the non-analytic and negative cubic term in the free energy that results in a large spontaneous spin magnetization. Finite spin-orbit interaction leads to the out-of-plane Ising order of the ferromagnetic phase. Our theoretical prediction is consistent with the recent experiment on electron-doped monolayers of MoS2 reported by Roch et al. 1 The proposed first order phase transition can also be tested by measuring the linear magnetic field dependence of the spin susceptibility in the paramagnetic phase which is a direct consequence of the non-analyticity of the free energy.

show abstract

Section: Introductionmentioning

confidence: 68%

“…[17][18][19] The results predicted in Refs. 17,18 are valid if the exchange inter-valley (EIV) interaction is negligible. The limit considered in Ref.…”

Section: Introductionmentioning

confidence: 68%

Exchange intervalley scattering and magnetic phase diagram of transition metal dichalcogenide monolayers

2019

View full text Add to dashboard Cite

show abstract

“…Whereas static response function govern the transport properties of the systems through the scattering by charge impurities in presence of screened Coulomb interaction 17,18 . Also many body properties such as dielectric function and collective excitation spectrum of systems with spin-orbit interaction (SOI) have several importance in terms of understanding the manybody correlations and observation of SOI effects in these systems [19][20][21][22][23] . Two dimensional electron gas (2DEG) with Rashba SOI (RSOI) and Dresselhaus SOI (DSOI) in a single quantum well host isotropic and anisotropic plasmon spectrum when considered one type of SOIs and both SOIs, respectively 22 .…”

Section: Introductionmentioning

confidence: 99%

Dynamical polarization and plasmons in noncentrosymmetric metals

Verma,

Kundu,

Ghosh

2020

Preprint

Self Cite

View full text Add to dashboard Cite

We study the dynamical polarization function and plasmon modes for spin-orbit coupled noncentrosymmetric metals such as Li2(Pd1−xPtx)3B. These systems have different Fermi surface topology for Fermi energies above and below the spin degenerate point which is also known as the band touching point (BTP). We calculate the exact dynamical polarization function numerically and also provide its analytical expression in the long wavelength limit. We obtain the plasmon dispersion within the framework of random phase approximation. In noncentrosymmetric metals, there is a finite energy gap in between intra and interband particle hole continuum for vanishing excitation wavevector. In the long wavelength limit, the width of interband particle hole continuum behaves differently for Fermi energies below and above the BTP as a clear signature of the Fermi surface topology change. We find a single undamped optical plasmon mode lying in between the intra and interband particle hole continuum for Fermi energies above and below the BTP within a range of parameters. The plasmon mode below the BTP has smaller velocity than that of above the BTP. It is interesting to find that as we tune the Fermi energy around the BTP, the plasmon mode becomes damped within a range of electron-electron interaction strength. For Fermi energies above and below the BTP, we also obtain an approximate analytical result of plasma frequency and plasmon dispersion which match well with their numerical counterparts in the long wavelength limit. The plasmon dispersion is ∝ q 2 with q being the wave vector for plasmon excitation in the long wavelength limit. We find that varying the carrier density with fixed electron-electron interaction strength or vice versa does not change the number of undamped plasmon mode, although damped plasmon modes can be more in number for some values of these parameters. We demonstrate our results by calculating the loss function and optical conductivity which can be measured in experiments.

show abstract

“…Magnetic instabilities in monolayers of TMDs were analyzed theoretically in Refs. [8][9][10][11]. Mixed ferromagnetic and valley polarized phases are predicted in the spin locking regime when the spin-orbit interaction (SOI) is much larger than the Fermi energy E F , the regime that is realistic for the hole doped TMDs [8,9] where the SOI gap is in order of few hundred meV [12][13][14][15].…”

mentioning

confidence: 99%

“…[8][9][10][11]. Mixed ferromagnetic and valley polarized phases are predicted in the spin locking regime when the spin-orbit interaction (SOI) is much larger than the Fermi energy E F , the regime that is realistic for the hole doped TMDs [8,9] where the SOI gap is in order of few hundred meV [12][13][14][15]. The opposite limit of small SOI compared to E F was considered in Refs.…”

mentioning

confidence: 99%

Magnetic phase transitions in two-dimensional two-valley semiconductors with in-plane magnetic field

Miserev,

Klinovaja,

Loss

2020

Preprint

View full text Add to dashboard Cite

A two-dimensional electron gas (2DEG) in two-valley semiconductors has two discrete degrees of freedom given by the spin and valley quantum numbers. We analyze the zero-temperature magnetic instabilities of two-valley semiconductors with SOI, in-plane magnetic field, and electron-electron interaction. The interplay of an applied in-plane magnetic field and the SOI results in non-collinear spin quantization in different valleys. Together with the exchange intervalley interaction this results in a rich phase diagram containing four non-trivial magnetic phases. The negative non-analytic cubic correction to the free energy, which is always present in an interacting 2DEG, is responsible for first order phase transitions. Here, we show that non-zero ground state values of the order parameters can cut this cubic non-analyticity and drive certain magnetic phase transitions second order. We also find two tri-critical points at zero temperature which together with the line of second order phase transitions constitute the quantum critical sector of the phase diagram. The phase transitions can be tuned externally by electrostatic gates or by the in-plane magnetic field.

show abstract

Spin response and collective modes in simple metal dichalcogenides

Cited by 9 publications

References 19 publications

Exchange intervalley scattering and magnetic phase diagram of transition metal dichalcogenide monolayers

Exchange intervalley scattering and magnetic phase diagram of transition metal dichalcogenide monolayers

Dynamical polarization and plasmons in noncentrosymmetric metals

Magnetic phase transitions in two-dimensional two-valley semiconductors with in-plane magnetic field

Contact Info

Product

Resources

About