Electronic And Magnetic Properties Of Cr_2-xTi_xSe₃ Single Crystals

The discovery of giant magnetoresistance greatly promoted the development of modern storage industries,but the stray field between the neighboring memory cells reduced the storage density of the ferromagnetic memory greatly.With the substantive progress made in the field of antiferromagnetic spinning electronics,the memory based on antiferromagnetic material is flourishing.There are a wide variety of chrome-based sulphic compounds,and their families show rich magnetic characteristics,magnetic properties cover ferromagnetic,ferrimagnetic and antiferromagnetic etc.,which is one of the ideal systems for studying magnetic properties of materials.This paper selects layered antiferromagnetic Cr₂Se₃ single crystal,which is stable at room temperature,as research objects.High quality single crystal was successfully growth by chemical vapor transportation.By studying their magnetic characteristics and electrical transportation properties,some novel physical properties are revealed,which can provide a foundation for future electronics applications.The main results are as follows:1.High-quality Cr₂Se₃ single crystals were grown by chemical vapor transportation.The crystals show metallicity and weak ferromagnetic properties both in plane and out of plane below Neél temperature.The field-cooled out-of-plane direction magnetization at 500 Oe and 10 K is 15 times larger than that of the in-plane one,indicating c-axis easy uniaxial magnetic anisotropy,which is supported by the magnetic hysteresis.Magnetic transport test indicates that magnetic resistance is negative and shows butterfly shape below 20 K,and couple with magnetization curve.The MR is about-12%at 2 K and 9 T.2.Single crystals with a nominal composition of Cr_1.97Ti_0.03Se₃ were grown by chemical vapor transportation.The resistivity and temperature relationship indicates that single crystals are semiconductor with activates energy E_a?7.5 me V.Under the action of an external magnetic field,the resistivity of 2 K changes by 2-3 orders.The ab plane shows antiferromagnetic characteristics,while the out-of-plane direction shows weak ferromagnetic properties near 42 K.When the temperature is lower than42 K,the system shows weak ferromagnetism and spin glass state.The field-cooled in-plane magnetization intensity is 1.8 times larger than that of out-of-plane direction at 2K and 500 Oe.MR presents a butterfly shape below 5 K.Cr_1.97Ti_0.03Se₃ single crystals have a huge negative magnetic resistance,and the MR is up to-97%at 2 K and 9 T.