相关论文: Coherent phonon dynamics at the martensitic phase …
An inelastic neutron scattering study of the lattice dynamics of the martensite phase of the ferromagnetic shape memory alloy, Ni2MnGa, reveals the presence of well-defined phasons associated with the charge density wave (CDW) resulting…
Magnetic shape memory Heusler alloys are multiferroics stabilized by the correlations between electronic, magnetic and structural order. To study these correlations we use time resolved x-ray diffraction and magneto-optical Kerr effect…
We present here results of temperature dependent high resolution synchrotron x-ray powder diffraction study of sequence of phase transitions in Ni2MnGa. Our results show that the incommensurate martensite phase results from the…
7M orthorhombic modulated structure in the martensite phase of Ni1.8Pt0.2MnGa is reported by powder neutron diffraction study, which indicates that it is likely to exhibit magnetic field induced strain. The change in the unit cell volume is…
Modulated phases occur in numerous functional materials like giant ferroelectrics and magnetic shape memory alloys. To understand the origin of these phases, we review and generalize the concept of adaptive martensite. As a starting point,…
The Prototypical magnetic memory shape alloy Ni$_2$MnGa undergoes various phase transitions as a function of temperature, pressure, and doping. In the low-temperature phases below 260 K, an incommensurate structural modulation occurs along…
The electronic structure of Mn_2NiGa has been studied using density functional theory and photoemission spectroscopy. The lower temperature tetragonal martensitic phase with c/a= 1.25 is more stable compared to the higher temperature…
We discuss modulation phasons as a possible source of unusual elastic behavior of five-layer modulated (10\,M) martensite of the Ni-Mn-Ga shape memory alloy. This material exhibits anomalous macroscopic shear compliance along specific…
We report on the impulsive generation of coherent optical phonons in CdTe0.68Se0.32 nanocrystallites embedded in a glass matrix. Pump probe experiments using femtosecond laser pulses were performed by tuning the laser central energy to…
In the present work, a combined theoretical and experimental study on Co$_{2}$PtGa Heusler alloy shows that it exhibits a martensite transition around 1320 K with a small thermal hysteresis (10 K). Dynamical stability of Co$_2$PtGa in the…
Using first-principles based Density Functional Theory (DFT), we have investigated the structural instabilities in the austenite phases of Mn$_{2}$Ni{\it X} ({\it X}= Al, Ga, In, Sn) magnetic shape memory alloys (MSMA). A complete softening…
A series of first principles calculations have been carried out in order to discuss electronic structure, phonon dynamics, structural instabilities and the nature of martensitic transformations of the Heusler alloys Ni$_2$Mn(Ga, Ge, Al) and…
The ultrafast switching of magnetization in multiferroic materials by a femtosecond laser could provide various advantages in photonics and magnonics. An efficient approach to control the light matter interaction is the modulation of…
The magnetic properties of Mn$_{2}$Ni$_{(1+x)}$In$_{(1-x)}$ ($x$ = 0.5, 0.6, 0.7) and Mn$_{(2-y)}$Ni$_{(1.6+y)}$In$_{0.4}$ ($y$ = -0.08, -0.04, 0.04, 0.08) shape memory alloys have been studied. Magnetic interactions in the martensitic…
We investigate optically induced phase transitions in the two-dimensional (2D) ferroelectric (FE) material Nb2O2I4 using real-time time-dependent density functional theory (rt-TDDFT). Our results demonstrate that tailored laser pulses can…
This study investigates the ultrafast dynamics of coherent phonons and phonon-polaritons in lithium niobate (LiNbO$_{3}$) crystals using reflective pump-probe spectroscopy with 25-fs time resolution. In addition to several coherent optical…
We apply grazing-incidence femtosecond x-ray diffraction to investigate the details of the atomic motion connected with a displacively excited coherent optical phonon. We concentrate on the low frequency phonon associated with the charge…
We predict the existence of a new ferromagnetic shape memory alloy Ga_2MnNi using density functional theory. The martensitic start temperature (T_M) is found to be approximately proportional to the stabilization energy of the martensitic…
We investigate coherent phonon oscillations of BaFe$_2$As$_2$ using optical pump-probe spectroscopy. Time-resolved optical reflectivity shows periodic modulations due to $A_{1g}$ coherent phonon of $c$-axis arsenic vibrations. Optical probe…
We employed femtosecond pump probe technique to investigate the dynamics of coherent optical phonons in iron garnet. A phenomenological symmetry-based consideration reveals that oscillations of the terahertz T2g mode are excited. Selective…