Magnetism on the thermal dynamics of 2D antiferromagnetic membranes

We developed a theoretical scheme of incorporating the magnetoelastic contribution into the thermal elastic dynamics for the thin membranes of 2D antiferromagnetic material with restricted geometry. We extended the elastic Gr\"uneisen relation into an effective version which includes the magnetic counterpart to the volume change of internal energy. Based on the specific heat and thermal conductivity from the elastic and magnetic origins we predicted the dependency of observables, such as effective Gr\"uneisen parameter, thermal expansion coefficient, and the damping factor, with respect to a wide range of temperature across the phase transition. Our model of analysis as been validated by applying to the case of FePS3 flake resonator and the theoretical predictions fits well with the reported experiment data

Controlling magnetism with light in zero orbital angular momentum antiferromagnet

Antiferromagnetic materials feature intrinsic ultrafast spin dynamics, making them ideal candidates for future magnonic devices operating at THz frequencies. A major focus of current research is the investigation of optical methods for the efficient generation of coherent magnons in antiferromagnetic insulators. In magnetic lattices endowed with orbital angular momentum, spin-orbit coupling enables spin dynamics through the resonant excitation of low-energy electric dipoles such as phonons and orbital resonances which interact with spins. However, in magnetic systems with zero orbital angular momentum, microscopic pathways for the resonant and low-energy optical excitation of coherent spin dynamics are lacking. Here, we consider experimentally the relative merits of electronic and vibrational excitations for the optical control of zero orbital angular momentum magnets, focusing on a limit case: the antiferromagnet manganese phosphorous trisulfide (MnPS3), constituted by orbital singlet Mn2þ ions. We study the correlation of spins with two types of excitations within its band gap: a bound electron orbital excitation from the singlet orbital ground state of Mn2þ into an orbital triplet state, which causes coherent spin precession, and a vibrational excitation of the crystal field that causes thermal spin disorder. Our findings cast orbital transitions as key targets for magnetic control in insulators constituted by magnetic centers of zero orbital angular momentum

Nanomechanical probing and strain tuning of the Curie temperature in suspended Cr2Ge2Te6-based heterostructures

Two-dimensional magnetic materials with strong magnetostriction are attractive systems for realizing strain-tuning of the magnetization in spintronic and nanomagnetic devices. This requires an understanding of the magneto-mechanical coupling in these materials. In this work, we suspend thin Cr2Ge2Te6 layers and their heterostructures, creating ferromagnetic nanomechanical membrane resonators. We probe their mechanical and magnetic properties as a function of temperature and strain by observing magneto-elastic signatures in the temperature-dependent resonance frequency near the Curie temperature, TC. We compensate for the negative thermal expansion coefficient of Cr2Ge2Te6 by fabricating heterostructures with thin layers of WSe2 and antiferromagnetic FePS3, which have positive thermal expansion coefficients. Thus we demonstrate the possibility of probing multiple magnetic phase transitions in a single heterostructure. Finally, we demonstrate a strain-induced enhancement of TC in a suspended Cr2Ge2Te6-based heterostructure by 2.5 ± 0.6 K by applying a strain of 0.026% via electrostatic force

Ultrafast laser-induced spin-lattice dynamics in the van der Waals antiferromagnet CoPS

CoPS3 stands out in the family of the van der Waals antiferromagnets XPS3 (X = Mn, Ni, Fe, and Co) due to the unquenched orbital momentum of the magnetic Co2+ ions, which is known to facilitate the coupling of spins to both electromagnetic waves and lattice vibrations. Here, using a time-resolved magneto-optical pump-probe technique, we experimentally study the ultrafast laser-induced dynamics of mutually correlated spins and lattice. It is shown that a femtosecond laser pulse acts as an ultrafast heater and, thus, results in the melting of the antiferromagnetic order. At the same time, the resonant pumping of the 4T1g → 4T2g electronic transition in Co2+ ions effectively changes their orbital momentum, giving rise to a mechanical force that moves the ions in the direction parallel to the orientation of their spins, thus generating a coherent Bg phonon mode at the frequency of about 4.7 THz

Thermo-Magnetostrictive Effect for Driving Antiferromagnetic Two-Dimensional Material Resonators

Magnetostrictive coupling has recently attracted interest as a sensitive method for studying magnetism in two-dimensional (2D) materials by mechanical means. However, its application in high-frequency magnetic actuators and transducers requires rapid modulation of the magnetic order, which is difficult to achieve with external magnets, especially when dealing with antiferromagnets. Here, we optothermally modulate the magnetization in antiferromagnetic 2D material membranes of metal phosphor trisulfides (MPS3), to induce a large high-frequency magnetostrictive driving force. From the analysis of the temperature-dependent resonance amplitude, we provide evidence that the force is due to a thermo-magnetostrictive effect, which significantly increases near the Neél temperature, due to the strong temperature dependence of the magnetization. By studying its angle dependence, we find the effect is observed to follow anisotropic magnetostriction of the crystal lattice. The results show that the thermo-magnetostrictive effect results in a strongly enhanced thermal expansion force near the critical temperature of magnetostrictive 2D materials, which can enable more efficient actuation of nano-magnetomechanical devices and can also provide a route for studying the high-frequency coupling among magnetic, mechanical, and thermodynamic degrees of freedom down to the 2D limi

Measurements belonging to the publication: High-frequency gas effusion through nanopores in suspended graphene

This folder consist of the measurements of the Pore dependence. The samples are:BLG_12-C : 16 pores of 25 nm diameterBLG_11-C : 8 pores of 50 nm diameterBLG_6-C : 4 pores of 100 nm diameterBLG_8-C : 2 pores of 200 nm diameterBLG_4-C : 1 pores of 400 nm diameterBLG_9-C : 3 pores of 200 nm diameterBLG_10-C : 4 pores of 200 nm diameterBLG_2-C : 1 pores of 200 nm diameterAnd inside each folder there are two subfolders, Data and Results. The Data folder contains the raw data in txt and dat.The Results folder consist on several things:&nbsp;-Images of the results obtained for the sample.&nbsp;-Element folder in which the measurements are ploted by elements.&nbsp;-Pressure folder where the measurements are ploted by pressures.&nbsp;-ResonanceFit folder with the data of the resonance frequency fit, where the first value is A, the second is the resonance, and the third is q-factor.&nbsp;-Model4 folder eith the data of the fit to the model4. This data can have three options:&nbsp;&nbsp;&nbsp;*if it has 2 values: first value a, second value t_th&nbsp;&nbsp;&nbsp;*if it has 5 values, the values are a, t_th, b, t_g, c.&nbsp;&nbsp;&nbsp;*if it has 8 values, the resonace fit values are added at the beginning, so the values are A, w_0, q, a, t_th, b, t_g, c.</p

Measurements belonging to the publication: High-frequency gas effusion through nanopores in suspended graphene

This folder consist of the measurements of the Pore dependence. The samples are:BLG_12-C : 16 pores of 25 nm diameterBLG_11-C : 8 pores of 50 nm diameterBLG_6-C : 4 pores of 100 nm diameterBLG_8-C : 2 pores of 200 nm diameterBLG_4-C : 1 pores of 400 nm diameterBLG_9-C : 3 pores of 200 nm diameterBLG_10-C : 4 pores of 200 nm diameterBLG_2-C : 1 pores of 200 nm diameterAnd inside each folder there are two subfolders, Data and Results. The Data folder contains the raw data in txt and dat.The Results folder consist on several things:&nbsp;-Images of the results obtained for the sample.&nbsp;-Element folder in which the measurements are ploted by elements.&nbsp;-Pressure folder where the measurements are ploted by pressures.&nbsp;-ResonanceFit folder with the data of the resonance frequency fit, where the first value is A, the second is the resonance, and the third is q-factor.&nbsp;-Model4 folder eith the data of the fit to the model4. This data can have three options:&nbsp;&nbsp;&nbsp;*if it has 2 values: first value a, second value t_th&nbsp;&nbsp;&nbsp;*if it has 5 values, the values are a, t_th, b, t_g, c.&nbsp;&nbsp;&nbsp;*if it has 8 values, the resonace fit values are added at the beginning, so the values are A, w_0, q, a, t_th, b, t_g, c.</p