The antiferromagnet (AFM) / ferromagnet (FM) interfaces are of central importance in recently developed pure electric or ultrafast control of FM spins, where the underlying mechanisms remain unresolved. Here we report the direct observation of Dzyaloshinskii-Moriya interaction (DMI) across the AFM/FM interface of IrMn/CoFeB thin films. The interfacial DMI is quantitatively measured from the asymmetric spin-wave dispersion in the FM layer using Brillouin light scattering. The DMI strength is enhanced by a factor of 7 with increasing IrMn layer thickness in the range of 1-7.5 nm. Our findings provide deeper insight into the coupling at AFM/FM interface and may stimulate new device concepts utilizing chiral spin textures such as magnetic skyrmions in AFM/FM heterostructures.Control of spins in ferromagnets (FMs) utilizing antiferromagnets (AFMs) is an emerging branch of spintronics [1][2][3][4][5] . By placing an AFM layer adjacent to the FM layer, the unique electric, magnetic and transport properties of the AFM may be used to control the FM layer via interfacial coupling. Conventionally, the AFM layer has mostly played a passive role in device operations by either improving the hardness of FM via exchange bias [6][7][8] or increasing the magnetic damping of FM through spin pumping [9][10][11][12][13] . More recently, the AFMs have been used as active control elements, leading to promising breakthroughs in the electric and ultrafast control of FM spins. For instance, electric current-induced magnetization switching of FM without an external magnetic field has been realized in the AFM/FM systems [1][2][3][4] . These pioneering experiments have been shown to generate the pure spin current in the AFM or at the AFM/FM interface 1,2,[14][15][16] and to utilize the exchange bias to break the switching symmetry [1][2][3][4] . Moreover, coherent spin precession in the FM layer can be effectively excited by an ultrafast spin-exchange-coupling torque across the AFM/FM interface 5 . The laser pulse perturbs the AFM spin arrangement, which in turn generates an intense and non-thermal transient torque acting on the FM spins. Despite these promising achievements, certain limitations such as the incomplete magnetization switching by current remain in the AFM/FM system. Thus, elucidating interaction mechanisms across the AFM/FM interface is not only important from a scientific point of view, but also of great technologic relevance.In heterostructures with broken spatial inversion symmetry, the interfacial Dzyaloshinskii-Moriya interaction (DMI) has been identified as an important mechanism leading to a host of interesting phenomena. DMI promotes non-collinear spin alignments and determines the chirality and dynamics of chiral spin textures [17][18][19] . For instance, DMI stabilizes the magnetic skrymions and domain walls in the Né el configuration with certain chirality and lends a mechanism for driving skrymion and domain wall motion via spin torques [20][21][22][23][24][25] . Similarly, DMI likely contributes to the current-in...

Many diseases involve either the formation of new blood vessels (e.g., tumor angiogenesis) or the damage of existing ones (e.g., diabetic retinopathy) at the microcirculation level. Optical-resolution photoacoustic microscopy (OR-PAM), capable of imaging microvessels in 3D in vivo down to individual capillaries using endogenous contrast, has the potential to reveal microvascular information critical to the diagnosis and staging of microcirculation-related diseases. In this study, we have developed a dedicated microvascular quantification (MQ) algorithm for OR-PAM to automatically quantify multiple microvascular morphological parameters in parallel, including the vessel diameter distribution, the microvessel density, the vascular tortuosity, and the fractal dimension. The algorithm has been tested on in vivo OR-PAM images of a healthy mouse, demonstrating high accuracy for microvascular segmentation and quantification. The developed MQ algorithm for OR-PAM may greatly facilitate quantitative imaging of tumor angiogenesis and many other microcirculation related diseases in vivo. M. Arbeit, "VEGF is essential for hypoxia-inducible factor-mediated neovascularization but dispensable for endothelial sprouting," Proc. Natl. Acad. Sci. U. S. A. 108(32), 13264-13269 (2011). 9. J. Folkman, "Angiogenesis in cancer, vascular, rheumatoid and other disease," Nat. Med. 1(1), 27-30 (1995 1182-1186 (1971). 11. J. W. Baish and R. K. Jain, "Cancer, angiogenesis and fractals," Nat. Med. 4(9), 984 (1998). 12. R. K. Jain, "Normalizing tumor vasculature with anti-angiogenic therapy: A new paradigm for combination therapy," Nat. Med. 7(9), 987-989 (2001)

The growing demands for optical anti-counterfeiting technology require the development of new environmentally friendly materials with single component, multimodal fluorescence and high stability. Herein, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 lead-free double perovskite material is reported as an efficient multimodal luminescence material with excitation-wavelength-dependent emission. When excited by 360 nm UV light, dual-emission is observed at 455 and 560 nm, which comes from the 3P1–1S0 transition of Sb3+ ions and self-trapped excitons (STEs), respectively. Under the 320 nm UV lamp, the microcrystals show only a blue emission centered at 455 nm. Therefore, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 double perovskite emits blue and yellow lights under the 320 and 360 nm UV lamp, respectively. Moreover, the obtained double perovskite shows a high PLQY up to 41% and excellent stability against both air and high temperature, which make it a promising anti-counterfeiting material.

A new class of single‐molecule magnets (SMMs) based on Dy‐oxide clusterfullerenes is synthesized. Three isomers of Dy2O@C82 with C s(6), C 3v(8), and C 2v(9) cage symmetries are characterized by single‐crystal X‐ray diffraction, which shows that the endohedral Dy−(µ2‐O)−Dy cluster has bent shape with very short Dy−O bonds. Dy2O@C82 isomers show SMM behavior with broad magnetic hysteresis, but the temperature and magnetization relaxation depend strongly on the fullerene cage. The short Dy−O distances and the large negative charge of the oxide ion in Dy2O@C82 result in the very strong magnetic anisotropy of Dy ions. Their magnetic moments are aligned along the Dy−O bonds and are antiferromagnetically (AFM) coupled. At low temperatures, relaxation of magnetization in Dy2O@C82 proceeds via the ferromagnetically (FM)‐coupled excited state, giving Arrhenius behavior with the effective barriers equal to the AFM‐FM energy difference. The AFM‐FM energy differences of 5.4–12.9 cm−1 in Dy2O@C82 are considerably larger than in SMMs with {Dy2O2} bridges, and the Dy∙∙∙Dy exchange coupling in Dy2O@C82 is the strongest among all dinuclear Dy SMMs with diamagnetic bridges. Dy‐oxide clusterfullerenes provide a playground for the further tuning of molecular magnetism via variation of the size and shape of the fullerene cage.

The interfacial Dzyaloshinskii-Moriya Interaction (DMI) in ultrathin magnetic thin film heterostructures provides a new approach for controlling spin textures on mesoscopic length scales. Here we investigate the dependence of the interfacial DMI constant on a Pt wedge insertion layer in Ta/CoFeB/Pt(wedge)/MgO thin films by observing the asymmetric spin wave dispersion using Brillouin light scattering. Continuous tuning of by more than a factor of three is realized by inserting less than one monolayer of Pt. The observations provide new insights for designing magnetic thin film heterostructures with tailored for controlling skyrmions and magnetic domain wall chirality and dynamics.

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Fe 3 O 4 /α-F e2 O 3 composites were synthesized by a one-step method. The composition and their performances were modified by adjusting the concentration of Fe 3+ (FeCl 3 •6H 2 O) in the precursor solution, effectively. Compared with single-phase Fe 3 O 4 and Fe 2 O 3 , the effective microwave absorbing ability of Fe 3 O 4 /α-Fe 2 O 3 composites is much widened in the range 1−18 GHz, which could stem from the enhanced dipolar polarization and interfacial polarization due to lattice dislocations at the interface of Fe 3 O 4 /α-Fe 2 O 3 . The minimum reflection loss (RL) of Fe 3 O 4 /α-Fe 2 O 3 composites reaches about −43.1 dB at a thickness of 2.0 mm, with the effective absorption band reaching 3.4 GHz (9.8−13.2 GHz). In the thickness of 1.5−3.2 mm, the width of the RL reaches 9.9 GHz (3.5−13.4 GHz). The results demonstrate that Fe 3 O 4 /α-Fe 2 O 3 composites could be a candidate to be used as absorbers with the microwave absorption band much widened.

We introduce a new method for analysis of X-ray fluorescence (XRF) spectra based on continuous wavelet transform filters, and the method is applied to the determination of toxic metals in pharmaceutical materials using hand-held XRF spectrometers. The method uses the continuous wavelet transform to filter the signal and noise components of the spectrum. We present a limit test that compares the wavelet domain signal-to-noise ratios at the energies of the elements of interest to an empirically determined signal-to-noise decision threshold. The limit test is advantageous because it does not require the user to measure calibration samples prior to measurement, though system suitability tests are still recommended. The limit test was evaluated in a collaborative study that involved five different hand-held XRF spectrometers used by multiple analysts in six separate laboratories across the United States. In total, more than 1200 measurements were performed. The detection limits estimated for arsenic, lead, mercury, and chromium were 8, 14, 20, and 150 μg/g, respectively.