Brillouin Scattering Studies of La_{0.77}Ca_{0.23}MnO_3 Across Metal-Insulator Transition

Temperature-dependent Brillouin scattering studies have been carried out on La_{0.77}Ca_{0.23}MnO_3 across the paramagnetic insulator - ferromagnetic metal (I-M) transition. The spectra show a surface Rayleigh wave (SRW) and a high velocity pseudo surface acoustic wave (HVPSAW) besides bulk acoustic waves (BAW). The Brillouin shifts associated with SRW and HVPSAW show blue-shifts, where as the frequencies of the BAW decrease below the I-M transition temperature (T_C) of 230 K. These results can be understood based on the temperature dependence of the elastic constants. We also observe a central peak whose width is maximum at T_C.Comment: 7 pages, 8 figure

High temperature behavior of Sr-doped layered cobaltites Y(Ba1-xSrx)Co2O5.5: phase stability and structural properties

In this article we present a neutron diffraction in-situ study of the thermal evolution and high-temperature structure of layered cobaltites Y(Ba, Sr)Co2 O5+{\delta}. Neutron thermodiffractograms and magnetic susceptibility measurements are reported in the temperature range 20 K <= T <= 570 K, as well as high resolution neutron diffraction experiments at selected temperatures. Starting from the as-synthesized samples with {\delta} ~ 0.5, we show that the room temperature phases remain stable up to 550 K, where they start loosing oxygen and transform to a vacancy-disordered "112" structure with tetragonal symmetry. Our results also show how the so-called "122" structure can be stabilized at high temperature (around 450 K) in a sample in which the addition of Sr at the Ba site had suppressed its formation. In addition, we present the structural and magnetic properties of the resulting samples with a new oxygen content {\delta} ~ 0.25 in the temperature range 20 K <= T <= 300 K

Incoherent Effect of Fe and Ni Substitutions in the Ferromagnetic-Insulator La0.6Bi0.4MnO3+d

A comparative study of the effect of Fe and Ni doping on the bismuth based perovskite La0.6Bi0.4MnO3.1, a projected spintronics magnetic semiconductor has been carried out. The doped systems show an expressive change in magnetic ordering temperature. However, the shifts in ferromagnetic transition (TC) of these doped phases are in opposite direction with respect to the parent phase TC of 115 K. The Ni-doped phase shows an increase in TC ~200 K, whereas the Fe-doped phase exhibits a downward shift to TC~95 K. Moreover, the Fe-doped is hard-type whereas the Ni-doped compound is soft-type ferromagnet. It is observed that the materials are semiconducting in the ferromagnetic phase with activation energies of 77 & 82 meV for Fe & Ni-doped phases respectively. In the presence of external magnetic field of 7 Tesla, they exhibit minor changes in the resistivity behaviours and the maximum isothermal magnetoresistance is around -20 % at 125 K for the Ni-phase. The results are explained on the basis of electronic phase separation and competing ferromagnetic and antiferromagnetic interactions between the various mixed valence cations.Comment: 18 pages including figure

Brillouin scattering studies in Fe3_3O4_4 across the Verwey transition

Brillouin scattering studies have been carried out on high quality single crystals of Fe$_3$O$_4$ with [100] and [110] faces in the temperature range of 300 to 30 K. The room temperature spectrum shows a surface Rayleigh wave (SRW) mode at 8 GHz and a longitudinal acoustic (LA) mode at 60 GHz. The SRW mode frequency shows a minimum at the Verwey transition temperature $T_V$ of 123 K. The softening of the SRW mode frequency from about 250 K to $T_V$ can be quantitatively understood as a result of a decrease in the shear elastic constant C$_{44}$, arising from the coupling of shear strain to charge fluctuations. On the other hand, the LA mode frequency does not show any significant change around $T_V$, but shows a large change in its intensity. The latter shows a maximum at around 120 K in the cooling run and at 165 K in the heating run, exhibiting a large hysteresis of 45 K. This significant change in intensity may be related to the presence of stress-induced ordering of Fe$^{3+}$ and Fe$^{2+}$ at the octahedral sites, as well as to stress-induced domain wall motion.Comment: 14 pages, 3 figures, accepted in Physical Review B 200

The Logic of U.S. Deployment in Norway: The Trump Administration and NATO’s Northern Front

Observers generally assume that domestic concerns or Donald Trump’s personality oriented his administration’s foreign policy. In this piece, I discuss the United States’s decision in 2017 to base military forces in Norway. I argue that the Trump administration’s decision is mainly explainable by balance-of-power motives and has little to do with domestic concerns. After showing the importance of Norway to the United States and describing the military balance of power in Northern Europe, this study tests competing IR theories. It is clear that realism and balance-of-power theory are far more amenable for describing U.S. policy toward Norway

Konstantin and Ivan Aksakovs' thoughts on the Russian State

The article is devoted to the publications from the collection of articles “Slavophils’ Theory of State” (Moscow, 1898): “The Note on the Internal Affairs in Russia Submitted to the Emperor Alexander II” by K.S. Aksakov (1817–1860), the controversial article “Slavophils’ Theory of State (a letter to the editorial staff)” by Professor A.D. Gradovsky (1841–1889), “The Answer to Mr. Gradovsky about his Analysis of  “The Note” by K.S. Aksakov” by I.S. Aksakov (1823–1886). On the basis of the given publications theoretical views of the brothers Aksakov on the Russian State and criticism of their views by A.D. Gradovsky are discussed.Being one of the first representatives of socio-legal thought in Russia I.S. Aksakov introduced the so-called third element – “society” into Slavophils’ doctrine alongside with such notions as “land” and “state”. In I.S. Aksakov’s opinion the structure of the Russian State should be based on the combination of the absolute autocratic power of the Russian Tsar and a vast development of the system of self-regulation which does not leave a chance for bureaucracy and officials’ arbitrariness to prosper. Besides, the necessity of the legal order should go along with the ideal of “internal truth” which must determine external juridical state laws

Konstantin and Ivan Aksakovs' thoughts on the Russian State

The article is devoted to the publications from the collection of articles “Slavophils’ Theory of State” (Moscow, 1898): “The Note on the Internal Affairs in Russia Submitted to the Emperor Alexander II” by K.S. Aksakov (1817–1860), the controversial article “Slavophils’ Theory of State (a letter to the editorial staff)” by Professor A.D. Gradovsky (1841–1889), “The Answer to Mr. Gradovsky about his Analysis of  “The Note” by K.S. Aksakov” by I.S. Aksakov (1823–1886). On the basis of the given publications theoretical views of the brothers Aksakov on the Russian State and criticism of their views by A.D. Gradovsky are discussed.Being one of the first representatives of socio-legal thought in Russia I.S. Aksakov introduced the so-called third element – “society” into Slavophils’ doctrine alongside with such notions as “land” and “state”. In I.S. Aksakov’s opinion the structure of the Russian State should be based on the combination of the absolute autocratic power of the Russian Tsar and a vast development of the system of self-regulation which does not leave a chance for bureaucracy and officials’ arbitrariness to prosper. Besides, the necessity of the legal order should go along with the ideal of “internal truth” which must determine external juridical state laws

Bullying or Mobbing: Is it Happening in Your Academic Library?

The behaviors of bullying and mobbing have only begun to rise in the public’s awareness or towards the legal standing of harassment. But, like harassment, bullying and mobbing can lead to the same results for employees: a loss of dignity, self-confidence and productivity, as well as an excessive amount of non-work related stress and other related health issues. Unfortunately, librarians, media specialists and other who work in libraries and information centers can also experience bullying and mobbing. It is important for people who work in libraries and information centers to understand bullying and mobbing, and toward that end this article provides definitions and a brief history of bullying and mobbing, presents scientific statistics, describes the characteristics of the various types of bullies, exposes who bullies tend to target and explores what is happening in the legal arena