  Well-protected magnetization, tunable quantum states and long coherence time
are desired for the use of magnetic molecules in spintronics and quantum
information technologies. In this work, endohedral fullerene molecules M@C28
with different transition metal cores were explored through systematic
first-principles calculations and spin dynamics analyses. Many of them have
stable magnetization, giant magnetic anisotropy energy and bias-tunable
structure. In particular, some of them may have coherence time up to several
milliseconds for their quantum spin states at high temperature (~10K) after
full consideration of spin-vibration couplings. These results suggest that
these M@C28 provide a rich pool for the development of single-molecule magnets,
magnetic molecular junctions, and molecular qubits.
