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Doctoral Thesis
DOI
10.11606/T.54.1988.tde-13102014-152807
Document
Author
Full name
Elisabeth Pavão de Castro
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1988
Supervisor
Committee
Camargo, Paulo Cesar de (President)
Eiras, José Antonio
Jordao, Jose Alberto Rodrigues
Li, Maximo Siu
Terrile, Maria Cristina
Title in Portuguese
Estudo das interações magneto-elásticas em ligas de cromo-vanádio
Keywords in Portuguese
Ligas cromo-vanadio; Interações magnetoelasticas; Ultrassom; Antiferomagnetismo itinerante
Abstract in Portuguese
Medidas de atenuação ultrassônica e constante elástica em ligas de Cr-V, utilizando técnicas de pulso eco foram realizadas e as transições na temperatura de Neel, TN, estudadas. Um modelo teórico é proposto para descrever os comportamentos da atenuação e constante elástica perto da transição em TN. De acordo com o modelo proposto a adição de vanádio diminui drasticamente o coeficiente de difusão, modificando a natureza da transição. Foram utilizadas amostras de cromo contendo 0,2%V; 0,5%V; 0,67%V; 1,0%V e 1,5%V. A partir da dependência aproximadamente linear de TN com a concentração de vanádio conclui-se que 3,3% V corresponderá à TN= 0K. O efeito do campo magnético até 4,5T revelou-se insuficientemente para a obtenção de monodomínio magnético e não causa nenhuma variação mensurável em TN
Title in English
Study of magnetoelastic interactions on chromium-vanadium alloys
Keywords in English
Chromium-vanadium alloys; Magneto-elastic interactions; Itinerant antiferromagnetism; Ultrasound
Abstract in English
Measurements of ultrasonic attenuation and elastic Constant in Cr-V alloys, using pulse echo techniques were realized and the transitions at the Neel temperature, TN, were studied. We propose a theoretical model which describe the behavior of the ultrasonic attenuation and elastic Constant near the transition in TN. According to the theoretical model the addition of Vanadium to chromium, drastically diminishes the diffusion coefficient thus changing the nature of the transition. It was used samples of chromium containing 0,2%V; 0,5%V; 0,67%V; 1,0%V and 1,5%V. From the approximately linear dependence of TN with the vanadium concentration it was concluded that 3,3%V corresponds to TN= 0. The effect of magnetic fields up to 4,5T was insufficient to produce single-Q samples, and did not cause any mensurable variation in TN
 
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Publishing Date
2014-10-20
 
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