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Theoretical Analysis of Magnetic Coupling in the Ti₂C Bare MXene.

ABSTRACT: The nature of the electronic ground state of the Ti₂C MXene is unambiguously determined by making use of density functional theory-based calculations including hybrid functionals together with a stringent computational setup providing numerically converged results up to 1 meV. All the explored density functionals (i.e., PBE, PBE0, and HSE06) consistently predict that the Ti₂C MXene has a magnetic ground state corresponding to antiferromagnetic (AFM)-coupled ferromagnetic (FM) layers. A spin model, with one unpaired electron per Ti center, consistent with the nature of the chemical bond emerging from the calculations, is presented in which the relevant magnetic coupling constants are extracted from total energy differences of the involved magnetic solutions using an appropriate mapping approach. The use of different density functionals enables us to define a realistic range for the magnitude of each of the magnetic coupling constants. The intralayer FM interaction is the dominant term, but the other two AFM interlayer couplings are noticeable and cannot be neglected. Thus, the spin model cannot be reduced to include nearest-neighbor interactions only. The Néel temperature is roughly estimated to be in the 220 ± 30 K, suggesting that this material can be used in practical applications in spintronics and related fields.

SUBMITTER: Garcia-Romeral N

PROVIDER: S-EPMC9969871 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature

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Theoretical Analysis of Magnetic Coupling in the Ti2C Bare MXene.

García-Romeral Néstor N Morales-García Ángel Á Viñes Francesc F Moreira Ibério de P R IPR Illas Francesc F

The journal of physical chemistry. C, Nanomaterials and interfaces 20230214 7

The nature of the electronic ground state of the Ti2C MXene is unambiguously determined by making use of density functional theory-based calculations including hybrid functionals together with a stringent computational setup providing numerically converged results up to 1 meV. All the explored density functionals (i.e., PBE, PBE0, and HSE06) consistently predict that the Ti2C MXene has a magnetic ground state corresponding to antiferromagnetic (AFM)-coupled ferromagnetic (F ...[more]

PMID: 36865991

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Project description:To propose an alternative method of thermoacoustic wave generation based on heating of magnetic nanoparticles (MNPs) using alternating magnetic field (AMF).The feasibility of thermoacoustic wave generation from MNPs by applying a short-burst of AMF or a frequency-modulated AMF is theoretically analyzed. As the relaxation of MNPs is strongly dependent upon the amplitude and frequency of AMF, either an amplitude modulated, fixed frequency AMF (termed time-domain AMF) or a frequency modulated, constant amplitude AMF (termed frequency-domain AMF) will result in time-varying heat dissipation from MNPs, which has the potential to generate thermoacoustic waves. Following Rosensweig's model of specific power loss of MNPs in a steady-state AMF, the time-resolved heat dissipations of MNPs of superparamagnetic size when exposed to a short bursting of AMF and∕or to a linearly frequency chirped AMF are derived, and the resulted acoustic propagation is presented. Based on experimentally measured temperature-rise characteristics of a superparamagnetic iron-oxide nanoparticle (SPION) matrix in a steady-state AMF of various frequencies, the heat dissipations of the SPION under time-domain and frequency-domain AMF configurations that could have practical utility for thermoacoustic wave generation are estimated.The initial rates of the temperature-rise of the SPION matrix were measured at an iron-weight concentration of 0.8 mg∕ml and an AMF frequency of 88.8 kHz to 1.105 MHz. The measured initial rates of temperature-rise were modeled by Rosensweig's theory, and projected to 10 MHz AMF frequency, at which a 1 μs bursting corresponding to a 1.55 mm axial resolution of acoustic detection could contain 10 complete cycles of AMF oscillation and the power dissipation is approximately 84 times of that at 1 MHz. Exposing the SPION matrix to a 1 μs bursting of AMF at 10 MHz frequency and 100 Oe field intensity would produce a volumetric heat dissipation of 7.7 μJ∕cm(3) over the microsecond duration of the AMF burst. If the SPION matrix is exposed to a 1 ms long AMF train at 100 Oe field intensity that chirps linearly from 1 to 10 MHz, the volumetric heat dissipation produced over each 2π phase change of the AMF oscillation is estimated to increase from 0.15 to 1.1 μJ∕cm(3) within the millisecond duration of the chirping of AMF.The heat dissipations upon SPION (∼1 mg∕ml iron-weight concentration) by a 1 μs bursting of 100 Oe AMF at 10 MHz and a 1 ms train of 100 Oe AMF that chirps linearly from 1 to 10 MHz were estimated to determine the potential of thermal-acoustic wave generation. Although thermoacoustic wave generation from MNPs by time- or frequency-domain AMF applications is predicted, the experimental generation of such a wave remains challenging.

Dataset Information

Theoretical Analysis of Magnetic Coupling in the Ti₂C Bare MXene.

Publications

Theoretical Analysis of Magnetic Coupling in the Ti<sub>2</sub>C Bare MXene.

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