  A simple and unambiguous test has been recently suggested [J. Phys. D:
Applied Physics, 52, 01LT01 (2018)] to check experimentally if a resistor with
memory is indeed a memristor, namely a resistor whose resistance depends only
on the charge that flows through it, or on the history of the voltage across
it. However, although such a test would represent the litmus test for claims
about memristors (in the ideal sense), it has yet to be applied widely to
actual physical devices. In this paper, we experimentally apply it to a
current-carrying wire interacting with a magnetic core, which was recently
claimed to be a memristor (so-called `$\Phi$ memristor') [J. Appl. Phys. 125,
054504 (2019)]. The results of our experiment demonstrate unambiguously that
this `$\Phi$ memristor' is not a memristor: it is simply an inductor with
memory. This demonstration casts further doubts that ideal memristors do
actually exist in nature or may be easily created in the lab.
