Multicaloric and coupled-caloric effects

The multicaloric effect refers to the thermal response of a solid material driven by simultaneous or sequential application of more than one type of external field.For practical applications,the multicaloric effect is a potentially interesting strategy to improve the efficiency of refrigeration devices.Here,the state of the art in multi-field driven multicaloric effect is reviewed.The phenomenology and fundamental thermodynamics of the multicaloric effect are well established.A number of theoretical and experimental research approaches are covered.At present,the theoretical understanding of the multicaloric effect is thorough.However,due to the limitation of the current experimental technology,the experimental approach is still in progress.All these researches indicated that the thermal response and effective reversibility of multiferroic materials can be improved through multicaloric cycles to overcome the inherent limitations of the physical mechanisms behind single-field-induced caloric effects.Finally,the viewpoint of further developments is presented.

Thermodynamic criterion for searching high mobility two-dimensional electron gas at KTaO_(3)interface

Two-dimensional electron gases(2 DEGs)formed at the interface between two oxide insulators present a promising platform for the exploration of emergent phenomena.While most of the previous works focused on SrTiO_(3-)based 2 DEGs,here we took the amorphous-ABO_(3)/KTaO_(3)system as the research object to study the relationship between the interface conductivity and the redox property of B-site metal in the amorphous film.The criterion of oxide-oxide interface redox reactions for the B-site metals,Zr,Al,Ti,Ta,and Nb in conductive interfaces was revealed:the formation heat of metal oxide,ⅢH_(f)^(o),is lower than-350 kJ/(mol O)and the work function of the metalΦis in the range of 3.75 eV<Φ<4.4 eV.Furthermore,we found that the smaller absolute value ofⅢH_(f)^(o)and the larger value ofΦof the B-site metal would result in higher mobility of the two-dimensional electron gas that formed at the corresponding amorphous-ABO_(3)/KTaO_(3)interface.This finding paves the way for the design of high-mobility all-oxide electronic devices.

Unipolar electric-field-controlled nonvolatile multistate magnetic memory in FeRh/(001)PMN-PT heterostructures over a broad temperature span

Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a unipolar electric field,the nonvolatile change in magnetization was nearly doubled compared with that obtained utilizing a conventional bipolar bias.Four stable nonvolatile magnetic states were obtained over a broad temperature span,from 320 to 390K,by adjusting the amplitude of the unipolar electric pulses,demonstrating the possibility of realizing a multistate nonvolatile magnetic memory in the FeRh/PMN-PT heterostructures.This work provides a new strategy for enhancing the magnetic response by utilizing unipolar electric fields and promotes the utilization of AFM-FM phase transition materials in multifunctional information storage and novel spintronic devices.

Palladium-Catalyzed Oxidative Annulation of 1-Hydroxy-o-Carborane withInternal Alkynes:Facile Synthesis of Carborane-Fused Oxaborolest

of main observation and conclusion A palladium catalyzed oxidative annulation of 1-hydroxy-o-carborane with internal alkynes via regioselective B(3)—H bond activation has been developed for facile synthesis of a series of QB-substituted carborane-fused oxaboroles.These molecules can undergo intramolecular oxidative dehydrogenative coupling to afford carborane-fused large n systems for potential applications in organic materials.The reaction mechanism is also proposed,involving hydroxy deprotonation,nucleopalladation of alkyne,regioselective electrophilic B—H substitution and reductive eiiimination.