Dark Matter Detection Using Magnetic Avalanche in Single-Molecule Magnets

Single-molecule magnets (SMMs) are crystals whose molecules act as self-contained, essentially non-interacting, magnets. There are over 100 different types of SMMs in existence with spins ranging from 1 to 45. When in the presence of an external magnetic field, their normally doubly degenerate magnetic potential shifts, causing a ground state and a metastable state. For a crystal in an external field above 0.1T and below its blocking temperature (<2K for Mn12-ac) this metastable state will remain stable for months to years. Only a small amount of added energy is required to cause a particle to overcome the barrier to the ground state, releasing Zeeman energy in the process. This released Zeeman energy causes neighboring molecules to repeat the process until the entire crystal is in the ground state. This is called a magnetic avalanche.

We propose a new low-energy threshold detector utilizing this magnetic avalanche phenomenon in SMMs. Similar to a traditional bubble chamber detector, this magnetic bubble chamber holds crystals in the metastable state so that energy of a known threshold will trigger a measurable avalanche. With the use of the right SMM, it is proposed that this detector will have a threshold in the meV-eV range, ideal for targeting Dark Photons. I will present our preliminary results using Mn12-ac, where we prove that SMMs can be used as a particle detector, thereby paving the way for this new generation of particle detectors.