There are two popular ways. 1. Andreev reflection, in which the purported half metal is contacted with with a superconducting lead. The cooper pairs (with no net spin) are reflected from the half metal. 2. Spin polarized positron spectroscopy. It is generally hard.

This paper discusses the positron measurement:

http://prb.aps.org/abstract/PRB/v42/i3/p1533_1

and this one the Andreev reflection:

http://prl.aps.org/abstract/PRL/v86/i24/p5585_1

Half-metallicity is an "accident" of the band structure, i.e. it is not related to a phase transition. As such you need to design a measure that is sensitive to the details of the band-structure. Note that there are several different definition of half-metals, and each one of them may require a different experimental verification. You can find more information in the paper attached here.

And here is the attached paper ...

Article Magnetic semiconductors and half-metals

is there any method or calculations that can help us in determining the half metallic nature using Vibrating Sample magnetometer

I don't think so. VSM measures an integral magnetic property of the sample, whereas spin polarization is a feature of the electronic structure. Particular in half metallic ferromagnets there is no 1:1 correspondence between both quantities.

However, VSM can give you some indirect information. You should make sure that the magnetic moment per unit cell is what you expect for your specific material. A lower value often indicates the presence of lattice defects and disorder which also affects the band gap. You can check these structural aspects by careful X-ray diffraction studies. If both VSM and XRD are good your material may be a HMF - at least in the bulk.

For a transport measurement, for example, in an MTJ, your HMF forms interfaces with other materials. This often gives rise to electronic interface states in the band gap, thereby reducing tha interfacial spin polarization as compared to the bulk value. So even if you succeed to obtain a HMF in the bulk, you cannot be sure that this property survives in a device.

One way is to make a ferromagnet/insulator/superconductor tunnel junction and measure the conductivity as a function of applied electrical bias across the junction in the presence of a suitable magnetic field.

The bandgap in the superconductor helps to resolve the spin polarised density of states in the ferromagnet. It is a well established technique for several decades now. For details of the experiment, you can refer to the papers listed below:

Phys. Rev. Lett., 25, 192 (1971)

Phys. Rev. B, 7, 318 (1973)

Phys. Rev. Lett., 25, 1270 (1970)

Phys. Rep., 238, 173 (1994)

Thank you to all ! After discussion and suggestion I got something about half metal. I want to learn much more about half metals. I need good DFT as well as experimental reference on half metallic system. After doping Eu my system host matrix bandstructure is showing half metallic behavior. Total bandstructure spin up and down bands are crossing Ef fermi level. I want to conclude my bandstructure results.

Shilendra

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