Search

Lithium-rich giant stars are rare and their existence challenges our understanding of stellar structure and evolution. We profit from the high-quality sample gathered with HARPS and UVES, in order to search for Li-rich giants and to identify the Li enrichment mechanisms responsible. We derive stellar parameters for 247 stars belonging to 32 open clusters, with 0.07 Ga < ages < 3.6 Ga. We employed the spectral synthesis technique code FASMA for the abundance analysis of 228 stars from our sample. We also determined ages, distances, and extinction using astrometry and photometry from Gaia and PARSEC isochrones to constrain their evolutionary stage. Our sample covers a wide range of stellar masses from 1 to more than 6 solar masses where the majority of the masses are above 2 solar masses. We have found 14 canonical Li-rich giant stars which have experienced the first dredge-up. This corresponds to 6% of our total sample, which is higher than what is typically found for field stars. Apart from the canonical limit, we use the maximum Li abundance of the progenitor stars as a criterion for Li enrichment. We find Li enhancement also among eight stars which have passed the first dredge up and show strong Li lines based on the fact that stars at the same evolutionary stage in the same cluster have significantly different Li abundances. We confirm that giants with higher Li abundance correspond to a higher fraction of fast-rotating giants, suggesting a connection between Li enhancement and stellar rotation as predicted by stellar models. Our Li-rich giants are found in various evolutionary stages implying that no unique Li production mechanism is responsible for Li enrichment but rather different intrinsic or external mechanisms can be simultaneously at play., accepted in A&A, online data will be available in CDS

Solid state compounds exhibiting multiple and coupled macroscopic orders, named multiferroics, represent a challenge for both theoretical and experimental modern condensed-matter physics. Spins and the electric polarisation in conventional magnetic and ferroelectric materials can be manipulated on their fundamental timescales, by means of femtosecond laser pulses. In view of the resounding success and popularity of the all-optical approach, it is only natural to wonder about the application of this scheme to study the intrinsic coupling between spins and charges in multiferroics. Deeply fundamental questions arise: can ultrashort laser pulses deterministically activate, enhance or suppress the magnetoelectric coupling on the femtosecond timescale? Can these processes be triggered in a fully coherent fashion, thus being unrestrained by any thermal load? Which mechanism of spin-charge coupling is most favourable to overcome these overarching and daunting challenges? This problem is interdisciplinary in nature, requiring contributions from materials science and condensed matter physics from both theoretical and experimental perspectives. High-quality materials suitable for optical investigations have to be identified, synthetized and characterised. General and valid models offer then a guide to the plethora of possible light-induced processes, resulting in the desired ultrafast multiferroic manipulations. Finally, healthy experimental schemes, able to unambiguously track the ultrafast dynamics of either the ferroelectric or the magnetic order parameter have to be developed and implemented. Our motivation to write this review is to lay a broad and multidisciplinary foundation, which may be employed as a starting point for non-equilibrium approaches to the manipulation of the multiferroicity on the femtosecond timescale. This was also one of the main goals of the COST Action MAGNETOFON, whose network constitutes the core of the authors of this review. The present work thus represents a part of the scientific legacy of MAGNETOFON itself.

Coherent THz optical lattice and hybridized phonon-magnon modes are triggered by femtosecond laser pulses in the antiferromagnetic van der Waals semiconductor FePS

In the 90's, theoretical studies motivated the use of the asymptotic-giant branch bump (AGBb) as a standard candle given the weak dependence between its luminosity and stellar metallicity. Because of the small size of observed asymptotic-giant branch (AGB) samples, detecting the AGBb is not an easy task. However, this is now possible thanks to the wealth of data collected by the CoRoT, Kepler, and TESS space-borne missions. It is well-know that the AGB bump provides valuable information on the internal structure of low-mass stars, particularly on mixing processes such as core overshooting during the core He-burning phase. In this context, we analysed ~ 4,000 evolved giants observed by Kepler and TESS, including red-giant branch stars and AGB stars, for which asteroseismic and spectrometric data are available. By using statistical mixture models, we detected the AGBb both in frequency at maximum oscillation power and in effective temperature. Then, we used the Modules for Experiments in Stellar Astrophysics MESA stellar evolution code to model AGB stars and match the AGBb occurrence with observations. From observations, we could derive the AGBb location in 15 bins of mass and metallicity. We noted that the higher the mass, the later the AGBb occurs in the evolutionary track, which agrees with theoretical works. Moreover, we found a slight increase of the luminosity at the AGBb when the metallicity increases, which complicates the use of the AGBb as a standard candle. By fitting those observations with stellar models, we noticed that low-mass stars (M < 1.0 $M_{\odot}$) require a small core overshooting region during the core He-burning phase. This core overshooting extent increases toward high mass, but above M > 1.5 $M_{\odot}$ we found that the AGBb location cannot be reproduced with a realistic He-core overshooting alone, and instead additional mixing processes have to be invoked., 20 pages, 7 figures, accepted in A&A

Phase-locked mid-infrared pulses tunable between 18 and 50 THz are generated with peak electric fields of 150 MV/cm. The compact and low-noise system aims at subcycle studies of matter under nonlinear driving or adiabatic bias.

The light-induced femtosecond dynamics of the sublattice magnetizations in the antiferromagnetically ordered phase of the semiconductor $\alpha$-MnTe is investigated theoretically as function of an external driving field. The electromagnetic field is coupled to optical modes and the concomitant atomic displacements modulate the Heisenberg exchange couplings. We derive the equations of motion for the time-dependent sublattice magnetization in spin wave theory and analyze the contributions from the driven magnon modes. The antiferromagnetic order parameter exhibits coherent longitudinal oscillations determined by the external driving frequency which decay due to dephasing. Including a phenomenological dissipative term to mimic spin-lattice relaxation processes leads to relaxation back to thermal equilibrium. We provide approximate analytic solutions of the resulting differential equations which allow us to understand the effect of the driving light pulse on the amplitude, frequency, and lifetime of the coherent spin dynamics., Comment: 20 pages, 15 figures

We investigate the role of domain walls in the ultrafast magnon dynamics of an antiferromagnetic NiO single crystal in a pump-probe experiment with variable pump photon energy. Analysing the amplitude of the energy-dependent photo-induced ultrafast spin dynamics, we detect a yet unreported coupling between the material's characteristic THz- and a GHz-magnon modes. We explain this unexpected coupling between two orthogonal eigenstates of the corresponding Hamiltonian by modelling the magneto-elastic interaction between spins in different domains. We find that such interaction, in the non-linear regime, couples the two different magnon modes via the domain walls and it can be optically exploited via the exciton-magnon resonance., 6 pages, 4 figures

Antiferromagnets have recently surged as the prominent material platform for the next generation spintronics devices. Despite the remarkable abundance of antiferromagnets and the variety of their spin textures in nature, they share a widely common, if not ubiquitous, feature. Magnetoelasticity, which is expressed as strictions of different origin, relativistic and/or exchange, significantly contributes to the magnetic anisotropy of antiferromagnets. Crucially, a general theoretical framework able to address the role of domain walls on the spin dynamics in antiferromagnets in the presence of magnetoelasticity is lacking. Here we tackle this problem developing a very general macroscopic phenomenological model. We demonstrate that the magnetoelasticity defines both the equilibrium and dynamical magnetic properties of easy-plane antiferromagnets in linear and nonlinear regimes. We employ our model to reproduce experimental results, showing that domain walls majorly affect the optically driven ultrafast nonlinear spin dynamics. Our model can be applied to a wide group of materials and, if properly extended, can be utilised to describe also other physical scenarios, key in the establishment of concepts for antiferromagnetic spintronics. published

We developed a table-top setup to perform magneto-optical pump-probe measurements with the possibility to independently tune the photon-energy of both pump and probe beams in the 0.5 eV-3.5 eV range. Our apparatus relies on a commercial turn-key amplified laser system, able to generate light pulses with duration shorter than or comparable to 100 fs throughout the whole spectral range. The repetition rate of the source can be modified via the computer in the 1 kHz to 1 MHz range. A commercial balanced detector is connected to a high-frequency digitizer, allowing for a highly-sensitive detection scheme: rotations of the probe polarization as small as 70 μdeg can be measured. Additionally, a DC magnetic field as high as 9 T and voltages in the kV regime can be applied on the sample. A cryostat allows us to precisely set the temperature of the specimen in the 4 K-420 K interval. We prove the performance of our setup by measuring the ultrafast demagnetization of a cobalt crystal as a function of a wide variety of experimental parameters.

We perform ultrafast pump-probe measurements on a nanometer-thick crystalline Bi-doped yttrium iron garnet film with perpendicular magnetic anisotropy. Tuning the photon energy of the pump laser pulses above and below the material’s band gap, we trigger ultrafast optical and spin dynamics via both one- and two-photon absorption. Contrary to the common scenario, the optically induced excitation induces an increase up to 20% of the ferromagnetic resonance frequency of the material. We explain this unexpected result in terms of a modification of the magnetic anisotropy caused by a long-lived photo-induced strain, which transiently and reversibly modifies the magnetoelastic coupling in the material. Our results disclose the possibility to optically increase the magnetic eigenfrequency in nanometer-thick magnets. published

In magnetoelectric and multiferroic materials, the magnetic degree of freedom can be controlled by electric field, and vice versa. A significant amount of research has been devoted to exploiting this effect for magnetoelectric data storage and manipulation devices driven by d.c. electric fields1–4. Aiming at ever-faster schemes of magnetoelectric manipulation, a promising alternative approach offers similar control on a femtosecond timescale, relying on laser pulses4–6 to control both the charge7,8 and the magnetic9,10 order of solids. Here we photo-induce magnetoelectricity and multiferroicity in CuB2O4 on a sub-picosecond timescale. This process is triggered by the resonant optical generation of the highest-energy magnetic excitations—magnons with wavevectors near the edges of the Brillouin zone. The most striking consequence of the photo-excitation is that the absorption of light becomes non-reciprocal, which means that the material exhibits a different transparency for two opposite directions of propagation of light. The photo-induced magnetoelectricity does not show any decay on the picosecond timescale. Our findings uncover a path for ultrafast manipulations of the intrinsic coupling between charges and spins in multiferroics 4 , which may reveal unexplored magnetic configurations and unravel new functionalities in terms of femtosecond optical control of magnetism. Pump–probe measurements of CuB2O4 reveal non-reciprocal directional dichroism, demonstrating the possibility to optically induce magnetoelectricity in a material on a femtosecond timescale.

We performed temperature-dependent optical pump–THz emission measurements in Y₃Fe₅O₁₂ (YIG)|Pt from 5 K to room temperature in the presence of an externally applied magnetic field. We study the temperature dependence of the spin Seebeck effect and observe a continuous increase as temperature is decreased, opposite to what is observed in electrical measurements, where the spin Seebeck effect is suppressed as 0 K is approached. By quantitatively analyzing the different contributions, we isolate the temperature dependence of the spin-mixing conductance and observe features that are correlated with the bands of magnon spectrum in YIG.

Author(s): Batignani, G; Pontecorvo, E; Bossini, D; Ferrante, C; Fumero, G; Cerullo, G; Mukamel, S; Scopigno, T | Abstract: Illuminating a magnetic material with femtosecond laser pulses induces complex ultrafast dynamical processes. The resulting optically detectable response usually contains contributions from both the optical properties and the magnetic degrees of freedom. Disentangling all the different components concurring to the generation of the total signal is a major challenge of contemporary experimental solid-state physics. Here, this problem is tackled, addressing the purely optical, nonmagnetic artifacts on the time resolved two-magnon stimulated Raman spectrum of an antiferromagnet, rationalizing the recent observation on the exchange energy modification upon photo-excitation. It is demonstrated how the genuine dynamics of the magnetic eigenmode can be disentangled from the nonlinear optical effects, generated by cross phase modulation, on the femtosecond timescale. The introduced approach can be extended for the investigation of l100nfs dynamic processes by means of coherent Ramannscattering.

The impulsive generation of two-magnon modes in antiferromagnets by femtosecond optical pulses, so-called femto-nanomagnons, leads to coherent longitudinal oscillations of the antiferromagnetic order parameter that cannot be described by a thermodynamic Landau-Lifshitz approach. We argue that this dynamics is triggered as a result of a laser-induced modification of the exchange interaction. In order to describe the oscillations we have formulated a quantum mechanical description in terms of magnon pair operators and coherent states. Such an approach allowed us to} derive an effective macroscopic equation of motion for the temporal evolution of the antiferromagnetic order parameter. An implication of the latter is that the photo-induced spin dynamics represents a macroscopic entanglement of pairs of magnons with femtosecond period and nanometer wavelength. By performing magneto-optical pump-probe experiments with 10 femtosecond resolution in the cubic KNiF$_3$ and the uniaxial K$_2$NiF$_4$ collinear Heisenberg antiferromagnets, we observed coherent oscillations at the frequency of 22 THz and 16 THz, respectively. The detected frequencies as a function of the temperature ideally fit the two-magnon excitation up to the N\'eel point. The experimental signals are described as dynamics of magnetic linear dichroism due to longitudinal oscillations of the antiferromagnetic vector., Comment: 25 pages, 10 figures

Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of spin waves at the crossing of the dispersion relations of spin waves and elastic waves. Finally, we demonstrate that the excitation mechanism of the optically-excited pure-elastic waves, which are the source of the observed magnetoelastic waves, is dissipative in nature., 5 pages, 4 figures

Optical femtosecond manipulation of magnetic order is attractive for the development of new concepts for ultrafast magnetic recording. Theoretical and experimental investigations in this research area aim at establishing a physical understanding of magnetic media in light-induced non-equilibrium states. Such a quest requires one to adjust the theory of magnetism, since the thermodynamical concepts of elementary excitations and spin alignment determined by the exchange interaction are not applicable on the femtosecond time-scale after the photo-excitation. Here we report some key milestones concerning the femtosecond optical control of spins in dielectric antiferromagnets, whose spin dynamics is by nature faster than that of ferromagnets and can be triggered even without any laser heating. The recent progress of the opto-magnetic effect in the sub-wavelength regime makes this exciting research area even more promising, in terms of both fundamental breakthroughs and technological perspectives.

Physical review / B 96(18), 184420 (2017). doi:10.1103/PhysRevB.96.184420, We report a high-resolution resonant inelastic extreme ultraviolet (EUV) scattering study of the quantum Heisenberg antiferromagnet KCoF$_3$. By tuning the EUV photon energy to the cobalt M$_{23}$ edge, a complete set of low-energy 3d spin-orbital excitations is revealed. These low-lying electronic excitations are modeled using an extended multiplet-based mean-field calculation to identify the roles of lattice and magnetic degrees of freedom in modifying the resonant inelastic x-ray scattering (RIXS) spectral line shape. We have demonstrated that the temperature dependence of RIXS features upon the antiferromagnetic ordering transition enables us to probe the energetics of short-range spin correlations in this material., Published by APS, Woodbury, NY

From the discovery of sub-picosecond demagnetization over a decade ago [1] to the recent demonstration of magnetization reversal by a single 40 femtosecond laser pulse [2], the manipulation of spins by ultra-short laser pulses has become a fundamentally challenging topic with a potentially high impact for future spintronics, data storage and manipulation and quantum computation [3]. It was realized that the femtosecond laser induced all-optical switching (AOS) as observed in ferrimagnets exploits the laser induced strongly non-equilibrium dynamics and the antiferromagnetic exchange interaction between their sublattices [4-6]. This opens the way to engineer new magnetic materials for AOS [7,8], though for real applications nanoscale control of inhomogeneities appears to be relevant [9]. Besides the intruiging technological implications of these observations, they broadened remarkably the frontiers of our fundamental knowledge of magnetic phenomena. The laser driven out-of-equilibrium states cannot be described in term of the well-established thermodynamical approach, which is based on the concepts of equilibrium and adiabatic transformations. Theoretical efforts, although in their infancy, have already demonstrated [5,6] that light-induced spin dynamics on the (sub)-picosecond time scale results in phenomena utterly forbidden in a thermodynamical framework. Another challenge is how to bring the optical manipulation of magnetic media to the required nanoscale. This is clearly a key element for the perspectives in terms of magnetic recording. In addition, it would allow to explore a novel regime of spin dynamics, since the investigation of magnets on the femtosecond time-scale and the nanometer length-scale simultaneously is unexplored. One experimental approach which may be successful makes use of wave-shaping techniques [10]. Recent results with engineered hybrid magnetic materials and nanofocusing via a plasmonic antenna showed the practical potential of AOS: the magnetization of domains as small as 50 nm was repeatedly reversed by a single laser pulse [11]. The process was fully deterministic, implying that each laser pulse totally reversed the magnetization of the domain in a reproducible way. Employing antennas provided another significant benefit, by decreasing the threshold laser energy required for the AOS to occur.

Unveiling the nature of the bosonic excitations that mediate the formation of Cooper pairs is a key issue for understanding unconventional superconductivity. A fundamen- tal step toward this goal would be to identify the relative weight of the electronic and phononic contributions to the overall frequency (\Omega) dependent bosonic function, \Pi(\Omega). We perform optical spectroscopy on Bi2212 crystals with simultaneous time- and frequency-resolution; this technique allows us to disentangle the electronic and phononic contributions by their different temporal evolution. The strength of the interaction ({\lambda}~1.1) with the electronic excitations and their spectral distribution fully account for the high critical temperature of the superconducting phase transition., Comment: 9 pages, 4 figures

We study the ultrafast spin dynamics in an antiferromagnet with sub-20 fs temporal resolution. Our experiments demonstrate the coherent manipulation of such spin excitations laying the foundations for a magnon-based nanotechnology operating in the 20 THz regime.

The reciprocal interaction between spins and light has long been one of the main topics in fundamental studies of magnetism. Recent developments of nanolitography and other experimental approaches have disclosed that the interaction of light with magnetic nanostructures is qualitatively different from the regime in which the size of the illuminated media is much larger than the wavelength. In particular, the subwavelength regime of light–spin interaction revealed the plasmon-mediated enhancement and emergence of new magneto-optical phenomena. Novel possibilities of optical control of magnetism on the nanometer scale via plasmonic resonances have emerged as well. Moreover, it was shown that femtosecond laser pulses are able to generate magnons with nanometer wavelengths and with wavevectors near the edges of the Brillioun zone. The use of optical radiation to either excite ultrafast spin dynamics or detect the magnetic properties of structures at the nanoscale began a new chapter in the fascinating story o...

Femtosecond stimulated Raman experiments on the antiferromagnetic system KNiF3 are implemented to understand how the exchange interaction — a crucial interaction that rules magnetic phenomena — is influenced by ultrafast optical excitation. Manipulating the macroscopic phases of solids using ultrashort light pulses has resulted in spectacular phenomena, including metal–insulator transitions1,2,3, superconductivity4 and subpicosecond modification of magnetic order5. The development of this research area strongly depends on the understanding and optical control of fundamental interactions in condensed matter, in particular the exchange interaction. However, disentangling the timescales relevant for the contributions of the exchange interaction and spin dynamics to the exchange energy, Eex, is a challenge. Here, we introduce femtosecond stimulated Raman scattering to unravel the ultrafast photo-induced dynamics of magnetic excitations at the edge of the Brillouin zone. We find that femtosecond laser excitation of the antiferromagnet KNiF3 triggers a spectral shift of the two-magnon line, the energy of which is proportional to Eex. By unravelling the photo-induced modification of the two-magnon line frequency from a dominating nonlinear optical effect, we find that Eex is increased by the electromagnetic stimulus.

Light fields at THz and mid-infrared frequencies allow for the direct excitation of collective modes in condensed matter, which can be driven to large amplitudes. For example, excitation of the crystal lattice, has been shown to stimulate insulator-metal transitions, melt magnetic order, or enhance superconductivity. Here, we generalize these ideas and explore the simultaneous excitation of more than one lattice mode, which are driven with controlled relative phases. This nonlinear mode mixing drives rotations as well as displacements of the crystal-field atoms, mimicking the application of a magnetic field and resulting in the excitation of spin precession in the rare-earth orthoferrite $ErFeO_3$. Coherent control of lattice rotations may become applicable to other interesting problems in materials research, for example as a way to affect the topology of electronic phases., Comment: 18 pages, 5 figures

Background: Environmental conditions early in life may imprint the circadian system and influence response to environmental signals later in life. We previously determined that a large springtime increase in solar insolation at the onset location was associated with a younger age of onset of bipolar disorder, especially with a family history of mood disorders. This study investigated whether the hours of daylight at the birth location affected this association. Methods: Data collected previously at 36 collection sites from 23 countries were available for 3896 patients with bipolar I disorder, born between latitudes of 1.4 N and 70.7 N, and 1.2 S and 413 S. Hours of daylight variables for the birth location were added to a base model to assess. the relation between the age of onset and solar insolation. Results: More hours of daylight at the birth location during early life was associated with an older age of onset, suggesting reduced vulnerability to the future circadian challenge of the springtime increase in solar insolation at the onset location. Addition of the minimum of the average monthly hours of daylight during the first 3 months of life improved the base model, with a significant positive relationship to age of onset. Coefficients for all other variables remained stable, significant and consistent with the base model. Conclusions: Light exposure during early life may have important consequences for those who are susceptible to bipolar disorder, especially at latitudes with little natural light in winter. This study indirectly supports the concept that early life exposure to light may affect the long term adaptability to respond to a circadian challenge later in life. (C) 2015 Elsevier Ltd. All rights reserved.

To know the properties of a particle or a wave, one should measure how its energy changes with its momentum. The relation between them is called the dispersion relation, which encodes essential information of the kinetics. In a magnet, the wave motion of atomic spins serves as an elementary excitation, called a spin wave, and behaves like a fictitious particle. Although the dispersion relation of spin waves governs many of the magnetic properties, observation of their entire dispersion is one of the challenges today. Spin waves whose dispersion is dominated by magnetostatic interaction are called pure-magnetostatic waves, which are still missing despite of their practical importance. Here, we report observation of the band dispersion relation of pure-magnetostatic waves by developing a table-top all-optical spectroscopy named spin-wave tomography. The result unmasks characteristics of pure-magnetostatic waves. We also demonstrate time-resolved measurements, which reveal coherent energy transfer between spin waves and lattice vibrations., Observation of the entire dispersion relation for spin waves remains a challenge which prevents the full understanding of many intriguing magnetic properties. Here, the authors develop a table-top all-optical approach to map out the dispersion curve of pure-magnetostatic waves in magnetic films.

Optical control of spins in the highly symmetric Heisenberg antiferromagnet KNiF3 is demonstrated. It is shown that Impulsive Stimulated Raman Scattering of light by magnons, combined with time-resolved magneto-optical detection, allows the generation and detection of antiferromagnetic resonances with unprecedented high sensitivity.

We present a femtosecond spectroscopic magneto-optical investigation of the coherent and incoherent spin dynamics in the antiferromagnetic dielectric ${\text{KNiF}}_{3}$. The pathways of the photoinduced energy flow to spins were controlled by tuning the pump photon energy. In particular, we demonstrate that laser pulses, with photon energy tuned to a nearly-zero-absorption region, excite the spin system without any signatures of heating of electrons or phonons. In this regime the ultrafast excitation of coherent spin waves is followed by a gradual increase of the spin temperature solely due to decoherence of the laser-generated magnons, as revealed by our simultaneous measurement of both the transversal and the longitudinal component of the spin dynamics.

We developed an ultrafast time-resolved magneto-optical (MO) imaging system with several millidegree resolution of light polarization angle, 100 fs time-resolution, and a micrometer spatial resolution. A CCD camera with about 10(6) pixels is used for detection and MO images with an absolute angle of the light polarization are acquired by the rotating analyzer method. By optimizing the analysis procedure with a least square method and the help of graphical processor units, this novel system significantly improves the speed for MO imaging, allowing to obtain a MO map of a sample within 15 s. To demonstrate the strength of the technique, we applied the method in a pump-and-probe experiment of all-optical switching in a GdFeCo sample in which we were able to detect temporal evolution of the MO images with sub-picosecond resolution.

Background: The onset of bipolar disorder is influenced by the interaction of genetic and environmental factors. We previously found that a large increase in sunlight in springtime was associated with a lower age of onset. This study extends this analysis with more collection sites at diverse locations, and includes family history and polarity of first episode. Methods: Data from 4037 patients with bipolar I disorder were collected at 36 collection sites in 23 countries at latitudes spanning 3.2 north (N) to 63.4 N and 38.2 south (S) of the equator. The age of onset of the first episode, onset location, family history of mood disorders, and polarity of first episode were obtained retrospectively, from patient records and/or direct interview. Solar insolation data were obtained for the onset locations. Results: There was a large, significant inverse relationship between maximum monthly increase in solar insolation and age of onset, controlling for the country median age and the birth cohort. The effect was reduced by half if there was no family history. The maximum monthly increase in solar insolation occurred in springtime. The effect was one-third smaller for initial episodes of mania than depression. The largest maximum monthly increase in solar insolation occurred in northern latitudes such as Oslo, Norway, and warm and dry areas such as Los Angeles, California. Limitations: Recall bias for onset and family history data. Conclusions: A large springtime increase in sunlight may have an important influence on the onset of bipolar disorder, especially in those with a family history of mood disorders. (C) 2014 Elsevier B.V. All rights reserved.

Ultrafast broadband transient reflectivity experiments are performed to study the interplay between the nonequilibrium dynamics of the pseudogap and the superconducting phases in Bi(2)Sr(2}Ca(0.92)Y(0.08)Cu(2)O(8+δ). Once superconductivity is established, the relaxation of the pseudogap proceeds ~2 times faster than in the normal state, and the corresponding transient reflectivity variation changes sign after ~0.5 ps. The results can be described by a set of coupled differential equations for the pseudogap and for the superconducting order parameter. The sign and strength of the coupling term suggest a remarkably weak competition between the two phases, allowing their coexistence.

Ultrafast broadband transient reflectivity experiments are performed to study the interplay between the nonequilibrium dynamics of the pseudogap and the superconducting phases in Bi(2)Sr(2}Ca(0.92)Y(0.08)Cu(2)O(8+δ). Once superconductivity is established, the relaxation of the pseudogap proceeds ~2 times faster than in the normal state, and the corresponding transient reflectivity variation changes sign after ~0.5 ps. The results can be described by a set of coupled differential equations for the pseudogap and for the superconducting order parameter. The sign and strength of the coupling term suggest a remarkably weak competition between the two phases, allowing their coexistence.

Contains fulltext : 117296.pdf (Publisher’s version ) (Open Access)