Temperature induced spin switching in SmFeO3 single crystal

Origins of multi-sublattice magnetism and superexchange interactions in double-double perovskite CaMnCrSbO6

The multi-sublattice magnetism and electronic structure in double-double perovskite compound CaMnCrSbO6is explored using density functional theory. The bulk magnetization and neutron diffraction suggest a ferrimagnetic order (TC∼49 K) between between Mn2+and Cr3+spins. Due to the non-equivalent Mn atoms (labelled as Mn(1) and Mn(2) which have tetrahedral and planar oxygen coordinations, respectively) and the Cr atom in the centre of distorted oxygen octahedron in the unit cell, the exchange interactions are more complex than that expected from a two sublattice magnetic system. The separations between the on-site energies of thed-orbitals of Mn(1), Mn(2) and Cr obtained from Wannier function analysis are in agreement with their expected crystal field splitting. While the DOS obtained from non spin-polarized calculations show a metallic character, starting from HubbardU = 0 eV the spin-polarized electronic structure calculations yield a ferrimagnetic insulating ground state. The band gap increases withUeff(U - J), thereby showing a Mott-Hubbard nature of the system. The inclusion of anti-site disorder in the calculations show decrease in band-gap and also reduction in the total magnetic moment. Due to the ∼90∘superexchange, nearest neighbour exchange constants obtained from DFT are an order of magnitude smaller than those reported for various magnetic perovskite and double-perovskite compounds. The Mn(1)-O-Mn(2) (out of plane and in-plane), Mn(1)-O-Cr and Mn(2)-O-Cr superexchange interactions are found to be anti-ferromagnetic, while the Cr-O-O-Cr super-superexchange is found to be ferromagnetic. The Mn(2)-O-Cr superexchange is weaker than the Mn(1)-O-Cr super-exchange, thus effectively resulting in ferrimagnetism. From a simple 3-site Hubbard model, we derived expressions for the antiferromagnetic superexchange strengthJAFMand also for the weaker ferromagneticJFM. The relative strengths ofJAFMfor the various superexchange interactions are in agreement with those obtained from DFT. The expression for Cr-O-O-Cr super-superexchange strength (J~SS), which has been derived considering a 4-site Hubbard model, predicts a ferromagnetic exchange in agreement with DFT. Finally, our mean field calculations reveal that assuming a set of four magnetic sub-lattices for Mn2+spins and a single magnetic sublattice for Cr3+spins yields a much improvedTC, while a simple two magnetic sublattice model yields a much higherTC.

Low field controllable continuous spin switching in the thulium-ytterbium single crystal

We report the spin reorientation transition (SRT) and the low field controllable continuous spin switching (SSW) of the Tm0.75Yb0.25FeO3 (TYFO) single crystal in this study. The SRT, characterized by the transition from Γ2(Fx, Cy, Gz)-Γ4(Gx, Ay, Fz), occurs within the temperature range of 20-27 K. Under an external magnetic field of 50 Oe, the SSW occurs along the c-axis at approximately 98 K due to the reversal of Tm3+ magnetic moment induced by the magnetic coupling change between Tm3+ and Fe3+, transitioning from a parallel to an antiparallel alignment. Notably, a continuous SSW is observed along the a-axis at low temperatures, which has not been previously reported in rare earth orthoferrites. This unique behavior can be easily manipulated by low magnetic fields within the temperature range of 2-20 K. Both the spin reorientation transition and spin switching phenomena in the TYFO single crystal arise from interactions between rare earth ions and iron ions and can be effectively regulated by applied low magnetic fields, making it a promising material for low-field spin devices.

Transient Magnetoelectric Coupling Induced by the Dynamic Intertwinement between Exchange Striction and Compensation in GdFeO3

In this study, we investigate the dynamic magnetoelectric (ME) coupling behaviors of GdFeO3 under pulsed magnetic fields. When a magnetic field is applied along the c-axis, and the temperature is near the compensation temperature (Tcomp = 3.5 K), we observe a subtle transition involving the reversal of Fe3+ moments at approximately 0.8 T in magnetization (M) measurements. This transition induces a corresponding jump in electrical polarization (P), which is not present in the static field measurements. The dynamic intertwining between M and P signifies a competition between antiferromagnetic (AFM) coupling between Gd3+ and Fe3+ moments and their Zeeman energies. The robust AFM coupling leads to the reversal of Fe3+ moments near Tcomp, triggering the abrupt change in P. Based on the exchange striction mechanism in the ferrimagnetic GdFeO3, we propose the possibility of achieving highly magnetic field sensitive ME coupling near the compensation temperature in ferrimagnetic multiferroic orthoferrites.

Field-Tuning Mechanisms of Spin Switching and Spin Reorientation Transition in Praseodymium-Erbium Orthoferrite Single Crystals

Field-tuning mechanisms of spin switching and spin reorientation (SR) transition were investigated in a series of high-quality single crystal samples of Pr_xEr_1-xFeO₃ (x = 0, 0.1, 0.3, 0.5) prepared using the optical floating zone method. The single crystal quality, structure, and axis orientation were determined by room-temperature powder X-ray diffraction, back-reflection Laue X-ray diffraction, and Raman scattering at room temperature. Magnetic measurements indicate that the type and temperature region of SR transition are tuned by introducing different ratios of Pr³⁺ doping (x = 0, 0.1, 0.3, 0.5). The trigger temperatures of spin switching and magnetization compensation temperature of Pr_xEr_1-xFeO₃ crystals can be adjusted by doping with different proportions of Pr³⁺. Furthermore, the trigger temperature of the two types of spin switching in Pr_0.3Er_0.7FeO₃ along the a-axis can be regulated by an external field. Meanwhile, the isothermal magnetic field-triggered spin switching effect is also observed along the a and c-axes of Pr_0.3Er_0.7FeO₃. An in-depth understanding of the magnetic coupling and competition between the R³⁺ and Fe³⁺ magnetic sublattices, within the RFeO₃ system, has important implications for advancing the practical applications of the relevant spin switching materials.

Low field control of spin switching and continuous magnetic transition in an ErFeO3 single crystal

The magnetic behavior of a rare-earth orthoferrite ErFeO₃ single crystal can be controlled by low magnetic fields from a few to hundreds of Oe. Here we investigated a high-quality ErFeO₃ single crystal in the temperature range of 5-120 K, with two types of spin switching in the field-cooled-cooling (FCC) and field-cooled-warming (FCW) processes below the temperature of the spin reorientation (SR) transition from Γ₄ to Γ₂ at 98-88 K. The magnitude of the applied magnetic fields can regulate two types of spin switching along the a-axis of the ErFeO₃ single crystal but does not affect the type and temperature range of the SR transition. An interesting "multi-step" type-II spin switching is observed in FCW under low magnetic fields (H < 18 Oe) just below the SR transition temperature, which is associated with the interaction and the change of magnetic configurations from rare-earth and iron magnetic sublattices. When the magnetic field is lower than 15 Oe, the type-II spin switching in the FCW process gradually changes to a continuous magnetic transition along the a-axis of the ErFeO₃ single crystal. As the magnetic field is reduced to less than 17 Oe, the type-I spin switching in the FCW process also transforms into a continuous magnetic transition. Understanding the magnetic reversal effects will help us explore the potential applications of these magnetic materials for future information devices.

A-Site Cation Size Effect on Structure and Magnetic Properties of Sm(Eu,Gd)Cr0.2Mn0.2Fe0.2Co0.2Ni0.2O3 High-Entropy Solid Solutions

Three high-entropy Sm(Eu,Gd)Cr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2O₃ perovskite solid solutions were synthesized using the usual ceramic technology. The XRD investigation at room temperature established a single-phase perovskite product. The Rietveld refinement with the FullProf computer program in the frame of the orthorhombic Pnma (No 62) space group was realized. Along with a decrease in the V unit cell volume from ~224.33 ų for the Sm-based sample down to ~221.52 ų for the Gd-based sample, an opposite tendency was observed for the unit cell parameters as the ordinal number of the rare-earth cation increased. The average grain size was in the range of 5–8 μm. Field magnetization was measured up to 30 kOe at 50 K and 300 K. The law of approach to saturation was used to determine the M_s spontaneous magnetization that nonlinearly increased from ~1.89 emu/g (Sm) up to ~17.49 emu/g (Gd) and from ~0.59 emu/g (Sm) up to ~3.16 emu/g (Gd) at 50 K and 300 K, respectively. The M_r residual magnetization and H_c coercive force were also determined, while the SQR loop squareness, k magnetic crystallographic anisotropy coefficient, and H_a anisotropy field were calculated. Temperature magnetization was measured in a field of 30 kOe. ZFC and FC magnetization curves were fixed in a field of 100 Oe. It was discovered that the T_mo magnetic ordering temperature downward-curve decreased from ~137.98 K (Sm) down to ~133.99 K (Gd). The spin glass state with ferromagnetic nanoinclusions for all the samples was observed. The <D> average and D_max maximum diameter of ferromagnetic nanoinclusions were calculated and they were in the range of 40–50 nm and 160–180 nm, respectively. The mechanism of magnetic state formation is discussed in terms of the effects of the A-site cation size and B-site poly-substitution on the indirect superexchange interactions.

Doping tuned spin reorientation and spin switching in praseodymium-samarium orthoferrite single crystals

We investigate the detailed analysis of the magnetic properties in a series of Pr_1-xSm_xFeO₃single crystals fromx= 0 to 1 with an interval of 0.1. Doping controlled spin reorientation transition temperatureT_SRΓ₄(G_x,A_y,F_z) to Γ₂(F_x,C_y,G_z) covers a wide temperature range including room temperature. A 'butterfly'-shape type-I spin switching with 180° magnetization reversal occurs below and above the magnetization compensation points inx= 0.4 to 0.8 compounds. Interestingly, in Pr_0.6Sm_0.4FeO₃single crystal, we find an inadequate spin reorientation transition accompanied by uncompleted type-I spin switching in the temperature region from 138 to 174 K. Furthermore, a type-II spin switching appears at 23 K, as evidenced from the magnetization curve in field-cooled-cooling (FCC) mode initially bifurcate from zero-field-cooled (ZFC) magnetization curve at 40 K and finally drops back to coincide the ZFC magnetization value at 23 K. Our current research reveals a strong and complex competition between Pr³⁺-Fe³⁺and Sm³⁺-Fe³⁺exchange interactions and more importantly renders a window to design spintronic device materials for future potential applications.

Spin reorientation transition and coupled spin-lattice dynamics of Sm0.6Dy0.4FeO3

In this work, we have presented a solid-solution of Sm0.6Dy0.4FeO3in the form of nano-particles having spin reorientation transition (SRT) at a temperature interval of 220-260 K. The lattice dynamics of Sm0.6Dy0.4FeO3have investigated by temperature-dependent x-ray diffraction and Raman spectroscopy. A negative thermal expansion at low temperatures has observed, which might be due to the interaction between Sm3+and Fe3+sublattice. Anomalous behavior in lattice parameters, octahedral tilt angle, and bond lengths have observed in the vicinity of SRT, which confirms the existence of magneto-elastic coupling in the system. The strong anomaly has observed in linewidth and phonon frequencies of Raman modes around SRT, which may be related to the spin-phonon coupling in Sm0.6Dy0.4FeO3. The contribution of SRT in lattice change and the presence of spin-phonon coupling can help to understand the correlation between the magnetic and structural properties of orthoferrite.

Synergistic effect of trivalent (Gd3+, Sm3+) and high-valent (Ti4+) co-doping on antiferromagnetic YFeO3

Monophasic polycrystalline powders of Y1-x R x Fe1-(4/3)y Ti y O3 (R = Sm, Gd; x = 0.05, 0.10, 0.15; y = 0.05) were successfully synthesized via a low temperature solid-state synthesis route. The X-ray diffraction and Raman spectroscopy studies indicate that all the calcined powders with R3+ (Gd3+, Sm3+) at Y3+ and Ti4+ at Fe3+ sites were crystallized in an orthorhombic phase associated with a change in lattice parameters. The Williamson-Hall method employed to calculate the strain revealed that the strain increased with the increased concentration of dopants ((Gd3+, Sm3+) at Y3+) compared to an increase in the size of crystallites, corroborating the findings of SEM. Analysis of diffuse reflectance spectra indicated a drop in bandgap from 1.93 eV to 1.86 eV and 1.96 eV to 1.91 eV for Gd, Ti co-doping and Sm, Ti co-doping respectively, demonstrating the capacity of the synthesized powders to absorb visible light. Absorbance spectra also revealed the existence of mixed states of Fe3+ and Fe4+ which was corroborated by XPS studies. The magnetic hysteresis loop analysis at room temperature illustrated that with co-doping, there is a strong enhancement in magnetization as well as coercivity, suggesting a strong transition from anti-ferromagnetic behaviour to ferromagnetic behaviour. Pertaining to the greatly improved optical and magnetic properties with the addition of (Gd3+, Sm3+) at Y3+ and Ti4+ at Fe3+ sites, these materials are anticipated to be of potential use in various applications.

Probing the low-temperature limit of the quantum anomalous Hall effect

Quantum anomalous Hall effect has been observed in magnetically doped topological insulators. However, full quantization, up until now, is limited within the sub-1 K temperature regime, although the material's magnetic ordering temperature can go beyond 100 K. Here, we study the temperature limiting factors of the effect in Cr-doped (BiSb)2Te3 systems using both transport and magneto-optical methods. By deliberate control of the thin-film thickness and doping profile, we revealed that the low occurring temperature of quantum anomalous Hall effect in current material system is a combined result of weak ferromagnetism and trivial band involvement. Our findings may provide important insights into the search for high-temperature quantum anomalous Hall insulator and other topologically related phenomena.

Spin phonon coupling in Mn doped HoFeO3 compounds exhibiting spin reorientation behaviour

An investigation has been carried out on the spin phonon coupling in a series of isostructural polycrystalline orthorhombic (Space group Pnma) compounds HoFe_1-X Mn _X O₃ (x  ⩽  0.6) exhibiting spin reorientation below Néel temperature (T _N), using magnetization, neutron diffraction, and Raman scattering techniques. Mn doping leads to an anomalous increase in the spin reorientation temperature (T _SR), shifting it close to room temperature from T _SR ~ 60 K for x  =  0 sample, and concomitant lowering of T _N. The T _SR is absent in samples for x  ⩾  0.5. The magnetic structure undergoes a transition at T _SR from Γ₄  →  Γ₁ in the Mn doped compounds as against Γ₄  →  Γ₂ observed in HoFeO₃ sample. In the region T  <  T _N an anomalous softening of Raman phonon modes viz., B _2g(5) and B _3g(3), identified with the stretching motion and breathing mode, respectively, of Fe/Mn-O₆ octahedra, is observed in compounds exhibiting spin-reorientation behaviour, indicating a spin-phonon coupling in these compounds. A quadratic correlation between the deviation of phonon frequency and variation of antiferromagnetic moment (Δω [Formula: see text] M ²) is observed in these compounds. The temperature evolution of the M2+  mode obtained from the analysis of neutron diffraction data based on symmetry adapted mode decomposition of the Pnma structure further corroborates the mode softening observation.

Frequency and temperature-dependent electric modulus spectroscopy of osmium-doped YbFeO3 structure

Orthoferrites have occupied important place in the material science and condensed matter physics investigations due to their unique features such as electrical, magnetic and optical. The present investigation illuminates light on the electrical properties of osmium (Os) doped YbFeO₃ (YbFO) rare-earth orthoferrite. The undoped YbFO and YbFe_1-x Os _x O₃ (YbFOO) (x  =  0.01 and 0.05) powders were synthesized via solid-state. X-ray diffractometer (XRD) has been utilized to examine the crystal structure of the YbFO and YbFOO powders. The cross sectional morphology of the obtained pellets was inspected via scanning electron microscope (SEM). Moreover, x-ray photoelectron spectroscopy was exploited to determine the oxidation states of the constituted elements. The electrical features for instance electrical modulus, dielectric constant and conductivity of the synthesized pellets were detailed at different frequencies and temperatures by dielectric/impedance spectroscopy studies. The x  =  0.01 Os doped sample exhibits higher dielectric constant and conductivity compared to other samples. Moreover, in order to explain conductivity mechanism of the studied samples, multiple conduction models are needed to employ.

Spin structure and spin Hall magnetoresistance of epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO3

We report a combined study of imaging the antiferromagnetic (AFM) spin structure and measuring the spin Hall magnetoresistance (SMR) in epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO₃. X-ray magnetic linear dichroism photoemission electron microscopy measurements reveal that the AFM spins of the SmFeO₃(1 1 0) align in the plane of the film. Angularly dependent magnetoresistance measurements show that SmFeO₃/Ta bilayers exhibit a positive SMR, in contrast to the negative SMR expected in previously studied collinear AFMs. The SMR amplitude increases linearly with increasing external magnetic field at higher magnetic fields, suggesting that field-induced canting of the AFM spins plays an important role. In contrast, around the coercive field, no detectable SMR signal is observed, indicating that the SMR of the AFM and canting magnetization components cancel out. Below 50 K, the SMR amplitude increases sizably by a factor of two as compared to room temperature, which likely correlates with the long-range ordering of the Sm ions. Our results show that the SMR is a sensitive technique for non-equilibrium spin systems of non-collinear AFMs.

Spin switching temperature modulated by the magnetic field and spontaneous exchange bias effect in single crystal SmFeO3

The spin switching and exchange bias effect were investigated in the rare earth orthoferrite SmFeO₃ composed of two antiferromagnetically coupled sublattices Sm³⁺ and Fe³⁺ with canted ferromagnetic moments and a temperature induced spin switching in single crystal SmFeO₃ was observed. The spin switching temperature was found to be modulated by exerting different magnetic fields below the compensation temperature ([Formula: see text]). This effect could be explained as the changes of energy barrier related to the magnetization direction under different magnetic fields. In the meantime, the coercivity displayed strong dependence on the maximum applied magnetic fields in the hysteresis measurement. In addition, spontaneous exchange bias effect (EB) was observed with the largest EB field value of 1.2 T, and the EB field changed its sign across the compensation point. Our results indicate that the magnetic properties of SmFeO₃ can be strongly affected and controlled by the temperature or the applied magnetic field during the measurement process, and it might lead to novel applications in magneto-optics, ultrafast switching, and magnetic sensing devices.

Strong magnetoelectric coupling in mixed ferrimagnetic-multiferroic phases of a double perovskite

Exploring new magnetic materials is essential for finding advantageous functional properties such as magnetoresistance, magnetocaloric effect, spintronic functionality, and multiferroicity. Versatile classes of double perovskite compounds have been recently investigated because of intriguing physical properties arising from the proper combination of several magnetic ions. In this study, it is observed that the dominant ferrimagnetic phase is coexisted with a minor multiferroic phase in single-crystalline double-perovskite Er₂CoMnO₆. The majority portion of the ferrimagnetic order is activated by the long-range order of Er³⁺ moments below T_Er = 10 K in addition to the ferromagnetic order of Co²⁺ and Mn⁴⁺ moments arising at T_C = 67 K, characterized by compensated magnetization at T_Comp = 3.15 K. The inverted magnetic hysteresis loop observed below T_Comp can be described by an extended Stoner-Wohlfarth model. The additional multiferroic phase is identified by the ferroelectric polarization of ~0.9 μC/m² at 2 K. The coexisting ferrimagnetic and multiferroic phases appear to be strongly correlated in that metamagnetic and ferroelectric transitions occur simultaneously. The results based on intricate magnetic correlations and phases in Er₂CoMnO₆ enrich fundamental and applied research on magnetic materials through the scope of distinct magnetic characteristics in double perovskites.

Giant spontaneous exchange bias obtained by tuning magnetic compensation in samarium ferrite single crystals

Spontaneous exchange bias (SEB) under zero field cooling (ZFC) has recently attracted lots of attention due to its underlying physics and potential applications. Here we report the giant SEB (GSEB) of SmFeO₃ single crystals by tuning magnetic compensation by temperature, which is rather convenient. A SEB field of up to 1 T at 3.9 K after ZFC (-1.4 T at 3.9 K after field cooling) was obtained. The SEB shows reciprocal relationship with remnant magnetization.

Spin-reorientation magnetic transitions in Mn-doped SmFeO3

Spin reorientation is a magnetic phase transition in which rotation of the magnetization vector with respect to the crystallographic axes occurs upon a change in the temperature or magnetic field. For example, SmFeO3 shows a magnetization rotation from the c axis above 480 K to the a axis below 450 K, known as the Γ4 → Γ2 transition. This work reports the successful synthesis of the new single-crystal perovskite SmFe0.75Mn0.25O3 and finds interesting spin reorientations above and below room temperature. In addition to the spin reorientation of the Γ4 → Γ2 magnetic phase transition observed at around TSR2 = 382 K, a new spin reorientation, Γ2 → Γ1, was seen at around TSR1 = 212 K due to Mn doping, which could not be observed in the parent rare earth perovskite compound. This unexpected spin configuration has complete antiferromagnetic order without any canting-induced weak ferromagnetic moment, resulting in zero magnetization in the low-temperature regime. M-T and M-H measurements have been made to study the temperature and magnetic-field dependence of the observed spin reorientation transitions.

Resolving the spin reorientation and crystal-field transitions in TmFeO3 with terahertz transient

Rare earth orthoferrites (RFeO₃) exhibit abundant physical properties such as, weak macroscopic magnetization, spin reorientation transition, and magneto-optical effect, especially the terahertz magnetic response, have received lots of attention in recent years. In this work, quasi-ferromagnetic (FM) and quasi-antiferromagnetic (AFM) modes arising from Fe sublattice of TmFeO₃ single crystal are characterized in a temperature range from 40 to 300 K, by using terahertz time-domain spectroscopy (THz-TDS). The magnetic anisotropy constants in ac-plane are estimated according to the temperature-dependent resonant frequencies of both FM and AFM modes. Here, we further observe the broad-band absorptions centered ~0.52, ~0.61, and ~1.15 THz below 110 K, which are reasonably assigned to a series of crystal-field transitions (R modes) of ground multiplets (⁶H₃) of Tm³⁺ ions. Specially, our finding reveals that the spin reorientation transition at a temperature interval from 93 to 85 K is driven by magnetic anisotropy, however, which plays negligible role on the electronic transitions of Tm ions in the absence of applied magnetic fields.

Magnetic-field dependence of strongly anisotropic spin reorientation transition in NdFeO3: a terahertz study

One of the biggest challenges in spintronics is finding how to switch the magnetization of a material. One way of the spin switching is the spin reorientation transition (SRT), a switching of macroscopic magnetization rotated by 90°. The macroscopic magnetization in a NdFeO3 single crystal rotates from Γ4 to Γ2 via Γ24 as the temperature is decreased from 170 to 100 K, while it can be switched back to Γ4 again by increasing the temperature. However, the precise roles of the magnetic-field induced SRT are still unclear. By using terahertz time-domain spectroscopy (THz-TDS), here, we show that the magnetic-field induced SRT between Γ4 and Γ2 is strongly anisotropic, depending on the direction of the applied magnetic field. Our experimental results are well interpreted by the anisotropy of rare-earth Nd(3+) ion. Furthermore, we find that the critical magnetic-field required for SRT can be modified by changing the temperature. Our study suggests that the anisotropic SRT in NdFeO3 single crystal provides a platform to facilitate the potential applications in robust spin memory devices.

Tunable room temperature magnetoelectric response of SmFeO3/poly(vinylidene fluoride) nanocomposite films

SmFeO₃/poly(vinylidene fluoride) composite films exhibit tunable magnetoelectric effects induced by strong strain interactions at the interfaces.

Thermally induced magnetization switching in Fe/MnAs/GaAs(001): selectable magnetic configurations by temperature and field control

Spintronic devices currently rely on magnetization control by external magnetic fields or spin-polarized currents. Developing temperature-driven magnetization control has potential for achieving enhanced device functionalities. Recently, there has been much interest in thermally induced magnetisation switching (TIMS), where the temperature control of intrinsic material properties drives a deterministic switching without applying external fields. TIMS, mainly investigated in rare-earth–transition-metal ferrimagnets, has also been observed in epitaxial Fe/MnAs/GaAs(001), where it stems from a completely different physical mechanism. In Fe/MnAs temperature actually modifies the surface dipolar fields associated with the MnAs magnetic microstructure. This in turn determines the effective magnetic field acting on the Fe overlayer. In this way one can reverse the Fe magnetization direction by performing thermal cycles at ambient temperatures. Here we use element selective magnetization measurements to demonstrate that various magnetic configurations of the Fe/MnAs/GaAs(001) system are stabilized predictably by acting on the thermal cycle parameters and on the presence of a bias field. We show in particular that the maximum temperature reached during the cycle affects the final magnetic configuration. Our findings show that applications are possible for fast magnetization switching, where local temperature changes are induced by laser excitations.