  We study the mixed state entanglement in a holographic axion model. We find
that the holographic entanglement entropy (HEE), mutual information (MI) and
entanglement of purification (EoP) exhibit very distinct behaviors with system
parameters. The HEE exhibits universal monotonic behavior with system
parameters, while the behaviors of MI and EoP relate to the specific system
parameters and configurations. We find that MI and EoP can characterize mixed
state entanglement better than HEE since they are less affected by thermal
effects. Moreover, we argue that EoP is more suitable for describing mixed
state entanglement than MI. Because the MI of large configurations are still
dictated by the thermal entropy, while the EoP will never be controlled only by
the thermal effects.
