| Records |
| Author |
Tiwari, S.; Vanherck, J.; Van de Put, M.L.; Vandenberghe, W.G.; Sorée, B. |
| Title |
Computing Curie temperature of two-dimensional ferromagnets in the presence of exchange anisotropy |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Physical review research |
Abbreviated Journal |
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| Volume |
3 |
Issue |
4 |
Pages |
043024 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We compare three first-principles methods of calculating the Curie temperature in two-dimensional (2D) ferromagnetic materials (FM), modeled using the Heisenberg model, and propose a simple formula for estimating the Curie temperature with high accuracy that works for all common 2D lattice types. First, we study the effect of exchange anisotropy on the Curie temperature calculated using the Monte Carlo (MC), the Green's function, and the renormalized spin-wave (RNSW) methods. We find that the Green's function method overestimates the Curie temperature in high-anisotropy regimes compared to the MC method, whereas the RNSW method underestimates the Curie temperature compared to the MC and the Green's function methods. Next, we propose a closed-form formula for calculating the Curie temperature of 2D FMs, which provides an estimate of the Curie temperature that is greatly improved over the mean-field expression for magnetic material screening. We apply the closed-form formula to predict the Curie temperature 2D magnets screened from the C2DB database and discover several high Curie temperature FMs, with Fe2F2 and MoI2 emerging as the most promising 2D ferromagnets. Finally, by comparing to experimental results for CrI3, CrCl3, and CrBr3, we conclude that for small effective anisotropies, the Green's-function-based equations are preferable, while for larger anisotropies, MC-based results are more predictive. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000707506500001 |
Publication Date |
2021-10-11 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
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ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
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Times cited |
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Open Access  |
OpenAccess |
| Notes |
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Approved |
Most recent IF: NA |
| Call Number |
UA @ admin @ c:irua:182522 |
Serial |
6975 |
| Permanent link to this record |
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| Author |
Tiwari, S.; Van de Put, M.L.; Sorée, B.; Vandenberghe, W.G. |
| Title |
Magnetic order and critical temperature of substitutionally doped transition metal dichalcogenide monolayers |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
npj 2D Materials and Applications |
Abbreviated Journal |
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| Volume |
5 |
Issue |
1 |
Pages |
54 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
Using first-principles calculations, we investigate the magnetic order in two-dimensional (2D) transition-metal-dichalcogenide (TMD) monolayers: MoS2, MoSe2, MoTe2, WSe2, and WS2 substitutionally doped with period four transition-metals (Ti, V, Cr, Mn, Fe, Co, Ni). We uncover five distinct magnetically ordered states among the 35 distinct TMD-dopant pairs: the non-magnetic (NM), the ferromagnetic with out-of-plane spin polarization (Z FM), the out-of-plane polarized clustered FMs (clustered Z FM), the in-plane polarized FMs (X-Y FM), and the anti-ferromagnetic (AFM) state. Ni and Ti dopants result in an NM state for all considered TMDs, while Cr dopants result in an anti-ferromagnetically ordered state for all the TMDs. Most remarkably, we find that Fe, Mn, Co, and V result in an FM ordered state for all the TMDs, except for MoTe2. Finally, we show that V-doped MoSe2 and WSe2, and Mn-doped MoS2, are the most suitable candidates for realizing a room-temperature FM at a 16-18% atomic substitution. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000650635200004 |
Publication Date |
2021-05-14 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
2397-7132 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
| Notes |
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Approved |
Most recent IF: NA |
| Call Number |
UA @ admin @ c:irua:179063 |
Serial |
7001 |
| Permanent link to this record |
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| Author |
Bizindavyi, J.; Verhulst, A.S.; Sorée, B.; Vandenberghe, W.G. |
| Title |
Thermodynamic equilibrium theory revealing increased hysteresis in ferroelectric field-effect transistors with free charge accumulation |
Type |
A1 Journal article |
| Year |
2021 |
Publication |
Communications Physics |
Abbreviated Journal |
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| Volume |
4 |
Issue |
1 |
Pages |
86 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
At the core of the theoretical framework of the ferroelectric field-effect transistor (FeFET) is the thermodynamic principle that one can determine the equilibrium behavior of ferroelectric (FERRO) systems using the appropriate thermodynamic potential. In literature, it is often implicitly assumed, without formal justification, that the Gibbs free energy is the appropriate potential and that the impact of free charge accumulation can be neglected. In this Article, we first formally demonstrate that the Grand Potential is the appropriate thermodynamic potential to analyze the equilibrium behavior of perfectly coherent and uniform FERRO-systems. We demonstrate that the Grand Potential only reduces to the Gibbs free energy for perfectly non-conductive FERRO-systems. Consequently, the Grand Potential is always required for free charge-conducting FERRO-systems. We demonstrate that free charge accumulation at the FERRO interface increases the hysteretic device characteristics. Lastly, a theoretical best-case upper limit for the interface defect density D-FI is identified. The ferroelectric field-effect transistor, which has attracted much attention for application as both a highly energy-efficient logic device and a non-volatile memory device, has often been studied within the framework of equilibrium thermodynamics. Here, the authors theoretically demonstrate the importance of utilizing the correct thermodynamic potential and investigate the impact of free charge accumulation on the equilibrium performance of ferroelectric-based systems. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000645913400001 |
Publication Date |
2021-04-30 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
2399-3650 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
| Notes |
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Approved |
Most recent IF: NA |
| Call Number |
UA @ admin @ c:irua:179005 |
Serial |
7031 |
| Permanent link to this record |
