Thermoremanence

If the microscopic dwell times are all much larger than the measurement time, then one probes the system as a static distribution of its parameters in order to deduce the state in which the system was prepared, by its previous temperature, applied field, and structuro-chemical history. For example, this would correspond to a remanence magnetization measurement, in the absence of time or relaxation effects. Alternatively, one can consider that all the particles in the sample that have microscopic dwell times much larger than the measurement time form a subgroup or subsystem that has reliably preserved a subsystem-specific remanence signal. Since dwell times are highly temperature dependent (Eqn. 2), partial thermoremanence measurements are a powerful tool to reconstruct a rock s thermomagnetic history. 

Hoffman KA (1975) Cation diffusion processes and self-reversal of thermoremanent magnetization in the ilmenite-hematite solid solution series. Geophys J Royal Astro Soc 41 65-80 Hoffman KA (1992) Self-Reversal of thermoremanent magnetization in the ilmenite-hematite system Order-disorder, synunetry, and spin aligmnent. J Geophys Res 97 10883-10895... 

SELF-REVERSED THERMOREMANENT MAGNETIZATION (SR-TRM) Mechanisms of self reversal Self-reversal in the ilmenite-hematite solid solution CHEMICAL REMANENT MAGNETIZATION (CRM)... 

FC), remanence (TRM measured after FC, IRM measured after ZFC) and slow (non-exponential) relaxation exist after magnetic perturbation (TRM denotes the thermoremanent magnetization, and IRM the isothermal remanent magnetization). 

Fig. 105. Isothermal remanence and thermoremanence of a-DyCu at 1.7 K. Vertical lines indicate the time variation in one minute (from Coey et al. 1981).

F.3.2. Magnetization under Moderate and High Applied Fields Remanence Magnetization and Coercive Field F.4.1. Remanence Magnetization Curves F.4.2. Isothermal Remanence Magnetization (IRM) studies F.4.3. Thermoremanence Magnetization (TRM) Studies F.4.4. Coercive Field F.4.5. Conclusions F.5. AC Susceptibility F.5.1. Models F.5.2. Experimental Results F.5.3, Conclusions... 

In the case of dc applied field, three different primary remanent magnetization curves can be measured. They are thermoremanent magnetization (TRM), isothermal remanent magnetization (IRM), and dc demagnetization (DcD) curves. ... 

For a time regime 1 t/tp t probed, the thermoremanent magnetization can be expressed in a dimensionless form as follows ... 

Some other measurements such as partial thermoremanent measurements for and NiO, and thermal decay of the remanence for... 

The AC susceptibility in ThFe Alg shows a strong step-like increase at IlOK but no sharp cusp. Neutron diffraction establishes antiferromagnetic coupling of the iron moments as well. Spin-glass features are clearly observable, predominantly in thermoremanent magnetization (Gal et al. 1990). 

Fig. 65. The thermoremanent magnetization at 4.2 K along the c-axis of a single crystal of LuFe204, YFFe O and YFCjOj, as a function of cooling field, (lida et al. 1989.)...

Fig. 66. The temperature dependence of the thermoremanent magnetization along the c-axis of LuFe O., for several values of the cooling field. (lida 1988.)...

Fig. 67. The temperature dependence of the saturation magnetization (open circles and a broken line) and the thermoremanent magnetization (solid lines) along the c-axis of LuFe204. The latter is induced by cooling from 250 K down to 4.2 K in an external magnetic field of 140 kOe and measured without field by successive heating-cooling cycles with increasing T, the maximum temperature of the cycle, (lida et al. 1987.)...

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