Magnetization field-cooled

Fig. 5 Magnetocapacitance and magnetoelectric effects in Tb MnCri, Magnetic field-induced change in the dielectric constant (a) and (b), electric polarization along the c and a axes, respectively (c) and (d). Magnetic fields are applied along the b axis. The data for (d) were collected after magnetic field cooling. The numbers in (d) denote the order of measurements at 9 K (from ref. 14).

Consider how the change of a system from a thennodynamic state a to a thennodynamic state (3 could decrease the temperature. (The change in state a —> f3 could be a chemical reaction, a phase transition, or just a change of volume, pressure, magnetic field, etc). Initially assume that a and (3 are always in complete internal equilibrium, i.e. neither has been cooled so rapidly that any disorder is frozen in. Then the Nemst heat... 

Electrical Connections. Electric current is brought from the transformers by air-cooled copper busbars and close to the electrode by water-cooled bus tubes and flexible cables, connecting to water-cooled copper contact plates at the electrode. The plates are held against the electrode by hydraulic pressure. The connectors are as short and as balanced as possible to allow cancelling of magnetic fields associated with individual conductors. 

All experiments were performed in a 1.9-T horizontal bore magnet (Oxford Instruments, Oxford, UK) with a dear bore diameter of 31 cm. Magnetic field gradients were produced by a 12-cm id water-cooled gradient set (Resonance Research, Billerica, MA, USA), capable of a maximum output of 300 mT m-1, and were driven by Techron 7700 amplifiers (Techron Inc., Elkhart, IN, USA). Rf excitation was accomplished using either a quadrature driven birdcage coil (Morris Instruments, Ottawa, ON, Canada), or an 8-tum laboratory-built solenoid coil, driven by an ENI LPI-10 1000 W amplifier or a Matec Model 525 class-C amplifier. 

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