Diffraction from ordered states of higher multipoles

Possible ways of identification are discussed of an electronic order of higher multipoles such as octupoles and hexadecapoles. A particularly powerful method is resonant X-ray scattering (RXS) using quadrupolar resonance processes called E2. The characteristic azimuthal angle dependence of Ce0.7La0.3B6 is interpreted as evidence of antiferro-octupole order. For PrRu4P12, eight-fold pattern against azimuthal angle is predicted if its metal-insulator transition is a consequence of a hexadecapole order. In non-resonant superlattice Bragg scattering, hexadecapole contribution may also be identified because of absence of quadrupole component.