through Transport Measurements at Extreme Conditions*

Exotic compounds that display novel quantum phenomena are the foundations of technological innovation. EuCd­­₂P₂ is a newly discovered strongly correlated electron system which displays colossal magnetoresistance (CMR) as an as-grown crystal despite failing to satisfy the accepted paradigm of archetypal CMR materials (i.e. La_0.75Ca_0.25MnO₃,  La_0.67Ca_0.33MnO₃ and other mixed-valence perovskite manganites). Colossal Magnetoresistance is the tendency of a material to experience a dramatic change in electrical resistance as a response to the presence of a magnetic field. This quantum phenomena lends itself to a robust increase in hard disk drive data density.

Because this sample doesn’t adhere to existing CMR theoretical modeling (namely the once standard double-exchange model) high pressure experimentation can be used to investigate the origin of CMR. Ambient pressure studies suggest the spin fluctuations above the material transition into A-type antiferromagnetism (AFM) as attributional phenomena for the CMR mechanism. In this explorative study not only have we sought to establish a better paradigm for CMR, but we have endeavored to discover new potential quantum ground states such as superconductivity in the crystal. To achieve these ends, we take electrical transport measurements of the material in a temperature range of 4-300 K and pressure range of 0-33 GPa through the use of standard high pressure devices and processes such as diamond anvil cells (DACs) and 4-probe electrical resistivity systems.

In this study, to complement supplementary x-ray diffraction (XRD) measurements which fail to associate the sample’s CMR behavior with structural phase transitions, we have taken electrical resistivity measurements which appear to suggest the phenomena’s electrical dependency.