Curie point of ferromagnets

Abstract

A student experiment is described concerning properties of ferromagnets near the Curie point. Gadolinium provides a good opportunity to determine the magnetic susceptibility above the transition point and to evaluate the critical exponent of the susceptibility. The temperature dependence of the electrical resistance of nickel at enhanced frequencies shows the influence of the magnetic properties of the sample on the skin depth. From the measurements, the phase transition is clearly seen and the temperature dependence of the magnetic permeability below the Curie point is available. Data on the resistance at an enhanced frequency reveal the phase transition in a nickel-based alloy. These items may be added to related student experiments described previously. Zusammenfassung. Ein Studentenexperiment inBeziehung der Eigenschaften eines Ferromagnetikums nahe des Curie-Punktes ist beschrieben. Gadolinium bietet eine gute Gelegenheit, die magnetische Suszeptibilitätüber der Ubergangstemperatur auszuwerten und den kritischen Exponent der Suszeptibilität berechnen. Die Temperaturabhängigkeit des elektrischen Widerstandes des Nickels in höheren Frequenzen demonstriert den Einfluß der magnetischen Eigenschaften der Probe auf die Skinschicht. Von den Messungen, der Phasenübergang ist klar und die Temperaturabhändigkeit der magnetischen Permeabilität unter der Curie-Temperatur kann berechnet werden. Die Daten des Widerstandes in höheren Frequenzen enthüllen den Phasenübergang in einer Nickellegierung. Vorher beschriebene Studentenexperimente können mit obigen Punkten ergänzt werden.

Ferroelectrics and the Curie-Weiss law

“…Ferromagnetic substances lose their spontaneous magnetization at temperatures above the Curie temperature, T C , and become paramagnetic [1]. This involves a phase transition in the crystal structure.…”

Quantum Critical Point in the Itinerant Ferromagnet Ni1−xRhx

“…Elemental Ni, which has a simple face-centered cubic structure, is known to order ferromagnetically below its Curie temperature T C = 627 K [24]. Upon alloying with Rh, the T C of Ni 1−x Rh x is quickly suppressed [25].…”

Protein gel electrophoresis in the undergraduate physics laboratory

“…7 The proteins in the mixture were precision standards and were prestained a blue color; the molar masses of the proteins were 10, 15, 25, 37, 50, 75, 100, 150, and 250 kg/ mol. The protein chain end-to-end distance ranged from approximately 75 Å ͑90 amino acids͒ to 1900 Å ͑2300 amino acids͒.…”

“…At 77 K, the saturation magnetization equals about 0.25 T. The Curie point is close to 270 K, in agreement with that obtained by measurements of the skin effect in the same Monel wire. 7 As a test of this setup, similar measurements were carried out with nickel and steel samples of the same geometry. Our magnetizing field, up to 16 mT, is insufficient to achieve saturation of the nickel sample.…”