Optical properties of organic superconductor K-(BETS)2FeBr4 /

K-(BETS)2FeBr4 is a quasi-2D charge transfer organic metal with interesting electronic and magnetic properties. It undergoes a transition to an antiferromagnetic (AF) state at ambient pressure at the Neel temperature (T^^) = 2.5 K, as well as to a superconducting (SC) state at 1.1 K [1]. The temperature dependence of the electrical resistivity shows a small decrease at T;v indicating the resistivity drops as a result of the onset of the ordering of Fe'*''" spins. A sharp drop in the resistivity at 1.1 K is due to its superconducting transition. The temperature dependence of the susceptibility indicates an antiferromagnetic spin structure with the easy axis parallel to the a-axis. The specific heat at zero-field shows a large peak at about 2.4 K, which corresponds to the antiferromagnetic transition temperature (Tat) and no anomaly is observed around the superconducting transition temperature (1.1 K) demonstrating that the magnetically ordered state is not destroyed by the appearance of another phase transition (the superconducting transition) in the 7r-electron layers [1], [2]. This work presents an investigation of how the low frequency electromagnetic response is affected by the antiferromagnetic and superconducting states, as well as the onset of strong correlation. The location of the easy axis of three samples was determined and polarized thermal reflectance measurements of these «-(BETS)2FeBr4 samples oriented with their vertical axis along the a- and c axes were then carried out using a *He refrigerator cryostat and a Martin-Puplett type polarizing interferometer at various temperatures (T = 0.5 K, 1.4 K. 1.9 K, 2.8 K) above and below the superconducting state and/or antiferromagnetic state. Comparison of the SC state to the normal state along the o- and c-axes indicates a rising thermal reflectance at low frequencies (below 10 cm"' ) which may be a manifestation of the superconducting energy gap. A dip-Hke feature is detected at low frequencies (below 15 cm"') in the thermal reflectance plots which probe the antiferromagnetic state along the two axes, and may be due to the opening of a gap in the excitation spectrum as a result of the antiferromagnetism. In another set of experiments, thermal reflectance measurements carried out along the a- and c-axes at higher temperatures (10 K-80 K) show that the reflectivity decreases with increasing temperature to 60 K (the coherence temperature) above which it increases again. Comparison of the thermal reflectance plots along the a- and c-axes at higher temperatures reveals an anisotropy between these two axes. The Hagen-Rubens thermal reflectance plots corresponding to an average over the ac-plane were calculated using experimental hterature resistivity values. Comparison of the Hagen-Rubens plots with the experimental thermal reflectance along the a- and c-axes indicates that both exhibit the general trend of a decrease in thermal reflectance with increasing frequency, however the calculated Hagen-Rubens thermal reflectance at different temperatures is much lower than the experimental curves.

Letter - Andrew Cowan to William Cowan

A letter from Andrew Cowan to his son William Cowan 29 Septemer 1841. The letter reads "Dear William, I have taken my pen the third time since I have received any word from you, my first letter was about the beginning of the year, and the second in the month of April with John Armstrong of Northhouse, he sailed from Liverpool the fifteen of that month with his sisters Jane and Jenny and their two children. I received a letter from him dated Cleavland in the State of Ohio the 6 of June. He did not intend stopping in that place. The leaves us all well for any thing that I know, but I have not heard from Andrew since March altho I have writen to him three months since your Mother and I are both sore faild altho we have tolerable good health for which we desire to be thankfull to the giver of all our mercies, which are new every day, that we may be found in Christs and clothed in his imputed righteousness at the last, for in him is only found true happyness. We have had another cold wet Summer and the crops is far back ------ not light, the price of -----is high and trade bad, but sheep and cattle are high. Cattle have not been higher since the French war, but the cattle trade is very bad at present and the opperatives out of imployment and consequently verrry badly of. If none of my former letters have reached you this will inform you that James is at Lanshawburn, and gets imployment all the year, he keeps a cow and five or six sheep, they have three children, Mary, Hannah, and Andrew; I was there after clipping time seeing them, they seem to be verry happy. James Lamb is well he was here the other night, he has got two letters from his son Adam this Summer; they are still in the same place and will finish their job this fall, and seem to be doing well, your Uncle Adam Scott and family are well. John was there lately there is little prospect of his getting to America as the money that was left him is not got yet and will not for some time, If ever this reach you, you must let us know how all the Scotch people that are near you, that went from this place of the Country are doing, as their freinds are anxious to hear from them, perticularly if you know what is becomed of Alexander Hoggs widow and family of ------hill, as I was desired to write to you about them - I got a letter from John Miller dated Gatt but I understand it is a long way from your place he was a gentleman and had the charge of a farm and seems verry ----- Now William if this ever reach you, you must excuse me for not filling this letter up, but if I receive an answer I promise to fill the next better, We all join in our love and respect to you and family. From your loving Father Andrew Cowan

Selected Articles from Beef Cattle Science Handbook Volume 19

The articles within the handbook are: "Livestock Psychology and Handling-Facility Design", "Design of Corrals, Squeeze Chutes, and Dip Vats", "Handling Feedlot Cattle", and "Reducing Transportation Stresses".