Scientists cannot theorize clearly if minerals and elements are arranged in plumes and strata inside mars, and the diameters that make up the martian condensed/fluid inner/outer strata and plumes, they don't know if there is something fluid and metallic [mobile electrically charged plumes of (probably) heavy elements (perhaps including iron, the 4th most common element on our world's surface), and heat from radioactive decay].
They will know more if there is any thermally driven geological movement inside the planet, including molten iron, if they can find any small temporal fluctuations in the magnetic field.
For the moment, a molten core only gives way to theories on "paleomagnetism, a latent magnetic crust of 10-125Km" deep stating that all the magnetism is left over from 4 billion years ago, and that certain zones have been de-magnetized by impact collision.
Meteorites de-magnetize the crust and it may be possible to date the chronology of the weakening molten core of mars from billions of years ago, to know how long ago the molten core was magnetic, and how fast it ceased being as fluid as it was.
Yt is not possible to determine detailed vertical variations of the magnetization of the Martian crust on the basis of magnetic data analysis alone, it is possible to estimate the thickness of the magnetic part of the Martian crust using other independent observations. The magnetic layer is bounded at the bottom by the depth to Curie isotherm of its major magnetic minerals, and at the top by the depth to the base of a near surface zone that has been demagnetized by impact-induced shock waves.
Some studies have demonstrated that the secondary magnetization acquired by the
lower crust in the absence of the core dynamo has little contribution to the observed magnetic anomalies.
The measurements of the magnetic crust are the only witness of the inner core's activity, and of it's spherical geometry:
Difficult measures are needed: 3D maps of the magnetic field, seismic data from multiple stations and meteorites, Magnetic basalt/igneous maps of 1/2/3 billion years chronology.
Some elements like Tg are twice as heavy as iron, melt at 2.5 times higher temps, and are conductive, so they would be much more likely than iron to be solid and to sink inwards if they are not melted into core alloys of metals. It's difficult to know the alloys and stratification of molten/solid materials that happen inside a planet.
The Maximum pressure at the center of mars is about <50 GigaPascals, because earth's core pressure is 330-360Gpa maximum, and mars is 10 times lighter. Here are images where you will see that H20 at the center of mars would need over 800'C to change from ice to water.
Iron needs to be over 3000K to melt inside mars at the very center , so we have no idea, all we know is that the magnetic field of earth is 40 times stronger than that of mars, which is a fairly good measure of the quantity and fluidity of metals inside mars.
Scientists have more questions than answers about earth and mars's core physics, even after many years of seismology.
For our planet, they have been able to determine that the center of the earth is solid iron/nickel, surrounded by a viscous and fluid outer core of similar material. If there is a lot of friction at the core of our planet, in a conductive medium, it is channeled in a N/S arrangement precisely matched with the rotation of the Earth. The Martian core is completely different, because it's magnetosphere is very irregular and lop-sided.
Here are some interesting facts about martian geology: http://www.planetary.org/blogs/emily-lakdawalla/2008/1710.html?referrer=https://www.google.fr/