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The dynamics of thermal and non-thermal lattice deformation of a nanometer thick polycrystalline aluminum film has been studied by means of femtosecond (fs) time-resolved electron diffraction. We utilized two different pump wavelengths: 800 nm, the fundamental of a Ti:sapphire laser, and 1250 nm generated by a home-made optical parametric amplifier. Our data show that although coherent phonons were generated under both conditions, the diffraction intensity decayed with the characteristic times of 0.9 ± 0.3 ps and 1.7 ± 0.3 ps under 800 nm and 1250 nm excitations, respectively. Because the 800 nm laser excitation corresponds to the strong interband transition of aluminum due to the 1.55 eV parallel band structure, our experimental data indicate the presence of non-thermal lattice deformation under 800 nm excitation, which occurs on a time-scale that is shorter than the thermal processes dominated by electron-phonon coupling under 1250 nm excitation.

We study the photocurrent induced by pulsed-light illumination (pulse duration is several nanoseconds) of single-crystal diamond containing nitrogen impurities. Application of additional continuous-wave light of the same wavelength quenches pulsed photocurrent. Characterization of the optically quenched photocurrent and its recovery is important for the development of diamond based electronics and sensing.

We report the observation of unidirectional magnetoresistance (UMR) in the ferrimagnetic insulator CoFe2O4(CFO)/Pt heterostructures, which stem from the giant interfacial Rashba–Edelstein effect. Furthermore, UMR has been found to show sign reversal and amplitude enhancement characteristics with decrease in temperature. We have ascribed it to the modulated distortion of Fermi contours due to pronounced spin canting at low temperatures. The presence of spin canting induced interfacial magnetic state has also been demonstrated by spin Hall magnetoresistance in CFO/Pt/Co/Al2O3 films. Our work reveals the interfacial magnetic state modulated UMR in CFO/Pt bilayers, thereby paving the way for extending its applications in ferrimagnet-based spintronic devices. [ABSTRACT FROM AUTHOR]

We have investigated the spin Hall magnetoresistance (SMR) in CoFe2O4/Pt heterostructures deposited on (001) MgO and (001) MgAl2O4 substrates, respectively. It is found that the interface non-collinear magnetic configurations should exist in both of the two films in the whole temperature range from 5 to 300 K but mainly dominate the spin transport properties at low temperature. Furthermore, the spin transport has featured epitaxial-strain-modified characteristics induced by different substrates, which has been investigated by magnetic curves, SMR, anisotropic magnetoresistance, and Hall effect measurements. [ABSTRACT FROM AUTHOR]

Thin films of Bi1.05La0.05FeO3 (BLFO) have been deposited on a CaRuO3 buffering layer on SrTiO3 using pulsed laser deposition. Then, a Pt thin layer was in situ sputtered on the surface of BLFO. The crystallization characteristic and surface morphology of the BLFO layer were checked. Spin transporting behaviors of the Pt/BLFO structure were investigated at room temperature. Interestingly, a magnetoresistance effect was observed at the interface of the Pt/BLFO bilayer. The spin mixing conductance at the interface between BLFO and Pt was estimated after a corrections of Pt thickness. This implies that the manipulation of spin–orbit coupling is possible at the interface of a single-phase multiferroic (e.g., BLFO) and a heavy metal (e.g., Pt). [ABSTRACT FROM AUTHOR]

Perovskite SrIrO3 is a special Dirac material with fascinating effects due to its strong electron correlation and spin–orbit coupling. In this work, a large magnetoresistance (MR) was observed not only in epitaxial SrIrO3 films but also in a SrIrO3/PbZr0.2Ti0.8O3 epitaxial heterostructure with a magnetic field applied perpendicular to the external electric field. The magnetoresistance of SrIrO3 (10 nm) and SrIrO3/PbZr0.2Ti0.8O3 (10 nm/30 nm) reach values as large as 40% and 110% at 9 T and 5 K, respectively. We believe that the unusual magnetoresistance is from the Dirac/Weyl state. Especially, the SrIrO3/PbZr0.2Ti0.8O3 bilayer shows negative magnetoresistance with strong oscillations close to the angle positions, where the magnetic field is parallel to the electric field at 1.8 K, which arises from the chiral anomaly. Based on first-principle calculations and study, the polarization field of PbZr0.2Ti0.8O3 can modulate the band structure of SrIrO3, which can modify the MR of SrIrO3. The SrIrO3/PbZr0.2Ti0.8O3 heterostructure accommodating both the ferroelectric property and the Dirac/Weyl state may open the avenue to manipulate the Dirac/Weyl properties via the electric polarization field. [ABSTRACT FROM AUTHOR]

The effect of the type of B-site substituent on the development of the ferroelectric state in the tetragonal part of the composition-temperature (x-T) diagram of (1-x)PbTiO3-xBi B 0.5 ′ B 0.5 ″ O3 solid solutions is analyzed by applying the second harmonic generation (SHG) method and Raman spectroscopy to three compounds with B 0.5 ′ B 0.5 ″ = Mg0.5Ti0.5, Ni0.5Ti0.5, and Ni0.5Zr0.5, having nearly the same tolerance factor and unit-cell tetragonality, at temperatures up to ∼1000 K. The results reveal the importance of B-site divalent dopants with an isotropic electron configuration for the enhancement of local symmetry breaking at the A site and a consequent increase in the Curie temperature at small x, regardless of the macroscopic tetragonality with respect to PbTiO3. [ABSTRACT FROM AUTHOR]

Magnetism control has a variety of applications in magnetic storage and spintronic devices. Instead of the control of direct magnetoelectric coupling via strain, voltage, and Dzyaloshinskii-Moriya interaction, the polarization-dependent coupling in multiferroic materials such as BiFeO3 is employed for the electric-field control of magnetizations in this work. A perpendicular magnetic anisotropy (PMA) has been realized in a BiFeO3/Al2O3/Pt/Co/Pt multiferroic structure at room temperature. Interestingly, a distinct change of coercivity field (∼400%) has been observed in the structure with opposite polarization directions, which can be attributed to the different oxidation degree at the Pt/Co interface. This spontaneous polarization-controlled switching not only provides us a platform to study the interfacial effect in multiferroic heterostructures but also paves the way to manipulate PMA or even spin orbit torque through oxygen vacancies. [ABSTRACT FROM AUTHOR]

We demonstrate the negative spin Hall magnetoresistance (SMR) observed in antiferromagnetic Cr2O3/Ta bilayers at low temperature. The SMR signals are changed from the positive to negative magnitude when monotonously reducing the temperature from 300 K to 50 K. The positive and negative SMR signals are expected to be associated with the two different ways for injection of the spin current, into the boundary ferromagnetic region and the bulk antiferromagnetic region of α-Cr2O3 (0001), respectively. The slopes of the abnormal Hall curves exhibit the same sign with the SMR signal. From the SMR ratio under 3 T, the spin mixing conductance at the Cr2O3/Ta interface is estimated to be 1.12 × 1014 Ω−1·m−2, which is comparable to the one observed in the Y3Fe5O12(YIG)/Pt structure and our early results of the Cr2O3/W structure. [ABSTRACT FROM AUTHOR]

In strongly correlated oxides, heterostructures provide a powerful route to manipulate the charge, spin, orbital, and lattice degrees of freedom to create distinctive functionalities. In this work, we have achieved atomically precise interface control in YBa2Cu3O7-x/La0.7Ca0.3MnO3 (YBCO/LCMO) heterostructures and find a hidden effective doping. This mechanism is responsible for higher Tc in the sample with the MnO2-terminated interface than in that with the La0.7Ca0.3O-terminated interface. The MnO2-terminated sample also shows a larger magnetic moment of Mn together with a lower valence state. For more than a decade, the control of Tc in these heterostructures prior to this work has been solely via the variation of YBCO or LCMO thickness. This work hints at an alternative way of exploiting and exploring the interactions between superconductivity and magnetism in this system. [ABSTRACT FROM AUTHOR]