New Fundamental Magnetic Law Uncovered

Amazing stuff!

"... However, a profound difference between the quantized lattice electric excitations—such as phonons—and spin excitations—such as paramagnetic and antiferromagnetic spin resonances and magnons—has now been unveiled in terms of their corresponding contributions to the static electric susceptibility and magnetic permeability. Viktor Rindert of Lund University in Sweden and his collaborators have derived and verified a formula that relates a material’s magnetic permeability to the frequencies of magnetic spin resonances. Whereas a well-established formula for the dielectric function—the electric equivalent of magnetic permeability—features a quadratic dependence on phonon frequencies, the new magnetic formula features a linear dependence on magnetic frequencies. Just as significant as the formula itself is the way in which it was validated, using a new optical technique that is set to be broadly useful for characterizing spintronic materials. ..."

From the abstract:

"We describe a magnetic relation in analogy to the well-known dielectric Lyddane-Sachs-Teller relation ... This magnetic relation follows directly from the model equations for nuclear induction due to fast oscillating electromagnetic fields ... and relates the static permeability with the product over all ratios of antiresonance and resonance frequencies associated with all magnetic excitations within a given specimen. The magnetic relation differs significantly from its dielectric analog where the static properties are related to ratios of the squares of resonance frequencies. We demonstrate the validity of the magnetic Lyddane-Sachs-Teller relation using optical magnetization data from terahertz electron magnetic resonance spectroscopic ellipsometry measurements in the presence of an external magnetic field on an iron-doped semiconductor crystal of gallium nitride."

Physics - New Fundamental Magnetic Law Uncovered "A new formula that connects a material’s magnetic permeability to spin dynamics has been derived and tested 84 years after the debut of its electric counterpart."

Magnetic Lyddane-Sachs-Teller Relation (open access)

Figure 1: Left: The original Lyddane-Sachs-Teller (LST) relation specifies the dielectric function in terms of the frequencies of lattice vibrations. Right: The new formula for magnetic LST specifies the magnetic permeability in terms of the precession frequencies of magnetic dipoles.