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   From: alt.fan.jai-maharaj@googlegroups.com   
      
   First observation of native ferroelectric metal   
      
   By FLEET   
   phys.org   
   Friday, July 5, 2019   
      
   Ferroelectric domains in a WTe2 single crystal (PFM   
   imaging). Credit: FLEET   
      
   In a paper released today in Science Advances, Australian   
   researchers describe the first observation of a native   
   ferroelectric metal: a native metal with bistable and   
   electrically switchable spontaneous polarization states—the   
   hallmark of ferroelectricity. The study found coexistence   
   of native metallicity and ferroelectricity in bulk   
   crystalline tungsten ditelluride (WTe2) at room   
   temperature. A van-der-Waals material that is both metallic   
   and ferroelectric in its bulk crystalline form at room   
   temperature has potential for nano-electronics   
   applications.   
      
   The study represents the first example of a native metal   
   with bistable and electrically switchable spontaneous   
   polarization states—the hallmark of ferroelectricity.   
      
   "We found coexistence of native metallicity and   
   ferroelectricity in bulk crystalline tungsten ditelluride   
   (WTe2) at room temperature," explains study author Dr.   
   Pankaj Sharma.   
      
   "We demonstrated that the ferroelectric state is switchable   
   under an external electrical bias and explain the mechanism   
   for 'metallic ferroelectricity' in WTe2 through a   
   systematic study of the crystal structure, electronic   
   transport measurements and theoretical considerations."   
      
   "A van der Waals material that is both metallic and   
   ferroelectric in its bulk crystalline form at room   
   temperature has potential for new nano-electronics   
   applications," says author Dr. Feixiang Xiang.   
      
   Ferroelectric backgrounder   
      
   Ferroelectricity can be considered an analogy to   
   ferromagnetism. A ferromagnetic material displays permanent   
   magnetism, and in layperson's terms, is simply, a 'magnet'   
   with north and south pole. Ferroelectric material likewise   
   displays an analogous electrical property called a   
   permanent electric polarisation, which originates from   
   electric dipoles consisting of equal, but oppositely   
   charged ends or poles. In ferroelectric materials, these   
   electric dipoles exist at the unit cell level and give rise   
   to a non-vanishing permanent electric dipole moment.   
      
   This spontaneous electric dipole moment can be repeatedly   
   transitioned between two or more equivalent states or   
   directions upon application of an external electric field—a   
   property utilised in numerous ferroelectric technologies,   
   for example nano-electronic computer memory, RFID cards,   
   medical ultrasound transducers, infrared cameras, submarine   
   sonar, vibration and pressure sensors, and precision   
   actuators.   
      
   Conventionally, ferroelectricity has been observed in   
   materials that are insulating or semiconducting rather than   
   metallic, because conduction electrons in metals screen-out   
   the static internal fields arising from the dipole moment.   
      
   Continues at:   
      
   https://phys.org/news/2019-07-native-ferroelectric-metal.html   
      
   Jai Maharaj, Jyotishi   
   Om Shanti   
   http://groups.google.com/group/alt.fan.jai-maharaj   
      
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