Ultrafast Optically Induced Ferromagnetic State in an Elemental Antiferromagnet

We present evidence for an ultrafast optically induced ferromagnetic alignment of antiferromagnetic Mn in Co/Mn multilayers. We observe the transient ferromagnetic signal at the arrival of the pump pulse at the Mn L3 resonance using x-ray magnetic circular dichroism in reflectivity. The timescale of the effect is comparable to the duration of the excitation and occurs before the magnetization in Co is quenched. Theoretical calculations point to the imbalanced population of Mn unoccupied states caused by the Co interface for the emergence of this transient ferromagnetic state

Accelerating the laser-induced demagnetization of a ferromagnetic film by antiferromagnetic order in an adjacent layer

We study the ultrafast demagnetization of Ni/NiMn and Co/NiMn ferromagnetic/antiferromagnetic bilayer systems after excitation by a laser pulse. We probe the ferromagnetic order of Ni and Co using magnetic circular dichroism in time-resolved pump-probe resonant x-ray reflectivity. Tuning the sample temperature across the antiferromagnetic ordering temperature of the NiMn layer allows us to investigate effects induced by the magnetic order of the latter. The presence of antiferromagnetic order in NiMn speeds up the demagnetization of the ferromagnetic layer, which is attributed to bidirectional laser-induced superdiffusive spin currents between the ferromagnetic and the antiferromagnetic layer

Cross-cultural Adaptation and Validation of the Persian Version of Voice Disability Coping Questionnaire (P-VDCQ): Introducing a New Instrument

Objectives: Coping is one of the important concepts in psychology, which is pertinent to how persons with illness manage the stress of that condition. Voice Disability Coping Questionnaire (VDCQ) is an assessment tool for quantifying coping strategies in those with voice disability. The purpose of the present study was to investigate reliability and validity of the Persian version of VDCQ (P-VDCQ). Method: Translation procedure was performed according to the World Health Organization guidelines, and then 138 persons (88 persons with voice disorders and 50 controls) completed the questionnaire. Psychometric properties of the P-VDCQ were investigated. Results: There was a significant difference between the mean value of patients with dysphonia and that of the control group. The results of test-result reliability indicated that there is a high correlation between repeated administration of the questionnaire (intraclass correlation coefficient = 89.7). Also, a high Cronbach's alpha coefficient (α = 0.94) revealed a good internal consistency. Participants' scores in this instrument had a moderate correlation with their scores on Voice Activity Participation Profile�Persian version (r = 0.41, P < 0.001). Conclusion: The P-VDCQ is a reliable and a valid instrument that can be used to investigate coping strategies of patients with dysphonia in clinical settings and for research purposes. © 2018 The Voice Foundatio

Synthesis, Characterization, and Application of Partially Blocked Amine-Functionalized Magnetic Nanoparticles

In this study, a novel technique was introduced for selective surface modification of amine-functionalized magnetic nanoparticles. The method was based on alignment of magnetic nanoparticles in an external magnetic field, which resulted in formation of chain-like assemblies in diluted suspensions. The aligned chains were then modified on the surface via reaction of isocyanate species with the particle functionalities. Finally, after removal from the reactor medium, particles with segmented distribution of surface functionalities were achieved. We named these partially blocked amine-functionalized magnetic nanoparticles as “Saturn” nanoparticles. Application of the particles in fabrication of magnetic assemblies was successfully demonstrated. Using methylene diphenyl diisocyanate (MDI) as the bridging agent, structures in different forms such as chains and filaments were produced by the Saturn particles and compared with cross-linked structures of the unmodified amine-functionalized particles. It is expected that this novel nanoparticle with its unique structure will have great potential in assembly fabrication with a variety of applications in biomedical fields

Thermal and Light Induced Spin Crossover Characteristics of a Functional Iron II Complex at Submonolayer Coverage on HOPG

Studies on the spin state switching characteristics of surface bound thin films of spin crossover SCO complexes are of interest to harness the device utility of the SCO complexes. Molecule substrate interactions govern the SCO of surface bound films in direct contact with the underlying substrates. In this study, we elucidate the role of molecule substrate interactions on the thermal and light induced spin state switching characteristics of a functional SCO complex [Fe H2B pz 2 2COOC12H25 bipy] pz pyrazole, C12 bpy dodecyl[2,2 amp; 8242; bipyridine] 5 carboxylate deposited at a submonolayer coverage on a highly oriented pyrolytic graphite HOPG substrate. A spin state coexistence of 42 low spin LS and 58 high spin HS is observed for the 0.4 ML deposit of the complex at 40 K, in contrast to the complete spin state switching observed in the bulk and in SiOx bound 10 nm thick films. Cooling the sample to 10 K results in a decrease of the LS fraction to 36 , attributed to soft X ray induced excited spin state trapping SOXIESST . Illumination of the sample with a green light amp; 955; 520 nm at 10 K caused the LS to HS switching of the remaining 36 LS complexes, by a process termed light induced excited spin state trapping LIESST . The mixed spin state in the submonolayer coverage of [Fe H2B pz 2 2COOC12H25 bipy] highlights the role of molecule HOPG substrate interactions in tuning the thermal SCO characteristics of the complex. The 100 HS state obtained after light irradiation indicates the occurrence of efficient on surface light induced spin switching, encouraging the development of light addressable molecular devices based on SCO complexe