Nevertheless, quantum physics is important in frustrated and low-dimensional magnetism, leading to exotic and potentially useful properties in insulators and metals.
We have experimentally quantified quantum fluctuations in an ordered, two-dimensional magnetic insulator and demonstrated that they can be tuned with magnetic fields. This is a fascinating example of the co-existence of frozen and dynamic quantum spin degrees of freedom. For localized. However, some materials develop relatively weak mean fields, and the quantum nature of the magnetism moments is preserved to temperatures well below those where magnetic.
This can happen for magnetic materials with low-dimensional or frustrated interaction topolo-. From the temperature dependence of the magnetic susceptibility,. This leads to a larger quantum-induced dispersion and also to an increase of continuum excitations. Field-tuned quantum fluctuations We applied magnetic fields nearly perpendicular to the square lattice planes and mapped the excitations as a function of magnetic field.
File of this pdf Ebook Advanced Computational Mtls Science Appl To Fission Fusion. Reactors is accessible inside certain variants at rajanikantfahadgq for. Advanced Fusion Reactors for Space Propulsion and Power Systems Nuclear fission processes typically result in producing energy in the form of heat that . well suited for fusion propulsion applications is the gasdynamic mirror (GDM). .. The pertinent physics capabilities include the plasma computational tools, the.
Our study shows that we can tune quantum fluctuations in an ordered antiferromagnet. While this is a coupling to an externally applied magnetic field, similar fluctuations in materials with mobile electrons, such as unconventional superconductors, may similarly couple to charge degrees of freedom and may be responsible for the intriguing properties in these fascinating materials.
References:  L. Faddeev, L. A Takhtajan, Phys. Haldane, Phys. Sandvik, R. Singh, Phys. Using inelastic neutron scattering, we have measured the long-lived spin waves at zero field. At the zone boundary, where the spin waves have a relatively short length scale, we observed a dispersion that reveals the presence of short-range quantum fluctuations Figure 2a. The dispersion can be explained by the presence of. Ronnow et al.
Tsyrulin et al. Andrea Carminati, Ahmad B. How does water enter the roots of plants? Existing models of root water-uptake predict a decrease of water nearer the roots, with water moving from wetter far away from the root surface to dryer adjacent to root surface regions. But neutron radiography has shown the opposite. During a drying period, the soil close to roots appeared wetter than the bulk soil.
Interestingly, the picture reversed after irrigation. Such observations are explained by mucilage exuded by roots. Mucilage favours water availability to plants during drying but, on the other hand, decreases water storage in the root zone after irrigation. The observed dynamics have potential applications for improving water-use efficiency and crop production. According to current concepts, water depletion should occur.
Water that is removed from the rhizosphere is then replaced by water flowing from more distant soil. In other words, water moves from wetter and more. This concept is well known and is included, in various degrees. This is true, of course, only if the soil around the roots is homogeneous, an assumption that all the existing models are based upon. These decreases in water potential and water content are extremely difficult to measure in situ at the required resolution, and the existing models of root water-uptake are therefore partly speculative.
Neutron radiography experiments Neutron radiography, with its high sensitivity to hydrous materials, offers a great opportunity for studying root and water distributions in situ [2, 3]. Figure 1: Neutron radiography of water distribution in a sample filled with a sandy soil and planted with a lupin.
Left: sample during. The interplay between magnetism and superconductivity continues to be a central issue in high-temperature superconductivity. The wire was made of a La1. We found that running a current through the wire, which suppresses the superconducting order parameter, increases the magnetic transition temperature.
Our results indicate that the Ginzburg-Landau coupling constant between the superconducting and magnetic order parameters is repulsive. Here we address these questions by studying the effect of a current running in a superconductor, I, on the magnetic phase transition temperature, Tm.
A current of the order of the second critical current Ic2 where the sample becomes normal decreases the superconducting order parameter. If the two orders interact, the magnetic order parameter would be expected to be influenced by the current and either increase or decrease, depending on the nature of the coupling between the two orders.
This, in turn, will increase or decrease Tm, respectively.
Measurements were taken on an 8-m-long wire made of a La1. The thickness of the film, 0. As shown in Figure 3, the application of a current of about 0.
Note also that, above Tm and below 4 K, the application of current has no effect on the asymmetry. The fact that the current increases Tm without broadening the transition rules out the possibility of temperature inhomogeneities.
The increase of Tm upon application of current implies that the orders are coupled repulsively. This is complementary to the effect of a strong magnetic field on doped samples, where the magnetic order is enhanced while the superconducting order Figure 2: Muon decay asymmetry measurements versus time, with high solid symbols and low open symbols currents.
However, since current, in contrast to magnetic field, does not couple directly to spin, the effect presented here is much simpler to analyze. For example, it shows that enhanced magnetism in an applied field could be a result of supercurrent in the bulk  and not necessarily due to magnetism in the vortex core .
Furthermore, analysis based on the Ginzburg-Landau GL model shows that the phase transition between AFM and SC must be close to the border between first and second order . References  F. Borsa, P. Carretta, J. Cho, F. Chou, Q. Hu, D. Johnston, A. Lascialfari, D.
Torgeson, R. Gooding, N. Salem, K. Vos, Phys. B 52 Figure 3: The magnetic phase transition with high 0.
Julien, F. Carretta, M. Horvatic, C. Berthier, C. Lin, Phys. As the temperature decreases, there is a clear increase in the muon spin depolarization rate, indicating that the sample is becoming magnetic. Morenzoni, F. Kottmann, D. Maden, B.