Critical Materials for Magnetism Critical Materials for Magnetism - PowerPoint PPT Presentation

Critical Materials for Magnetism Critical Materials for Magnetism J. M. D. Coey Physics Department and CRANN, Trinity College Dublin 2, Ireland 1 . Materials used for applications of magnetism Permanent magnets Soft magnets Magnetic recording 2. Permanent magnets — filling the gap 3. Perpendicular magnetic media and memory www.tcd.ie/Physics/Magnetism Tokyo, 21xi 2011

1 Introduction 2 Magnetostatics 3 Magnetism of the electron 4 The many-electron atom 5 Ferromagnetism 6 Antiferromagnetism and other magnetic order 7 Micromagnetism 8 Nanoscale magnetism 9 Magnetic resonance 10 Experimental methods 11 Magnetic materials 12 Soft magnets 13 Hard magnets 14 Spin electronics and magnetic recording 612 pages. Available now. 20% discount 15 Other topics for INTERMAG. Order direct for £40 + p&p Appendices, conversion tables. www.cambridge.org/9780521816144

Critical raw materials – – EU report EU report Critical raw materials * Platinum group metals � Germanium � Tantalum Tokyo, 21xi 2011

1. 1. Materials used for applications Materials used for applications Materials used for applications 1. 1. Materials used for applications of magnetism of magnetism of magnetism of magnetism

Magnetic Periodic Table 1 H 2 He 4.00 1.00 Atomic Number 66 Dy Atomic symbol 4 Be 5 B 6 C 7 N 8 O 9 F 10 Ne 3 Li Atomic weight 162.5 Typical ionic change 3 + 4 f 9 6.94 9.01 10.81 12.01 14.01 16.00 19.00 20.18 Antiferromagnetic T N (K) 179 85 Ferromagnetic T C (K) 1 + 2 s 0 2 + 2 s 0 35 11 Na 12 Mg 13 Al 14 Si 15 P 16 S 17 Cl 18 Ar 22.99 24.21 26.98 28.09 30.97 32.07 35.45 39.95 1 + 3 s 0 2 + 3 s 0 3 + 2 p 6 32 Ge 19 K 20 Ca 21 Sc 22 Ti 23 V 24 Cr 25 Mn 26 Fe 27 Co 28 Ni 29 Cu 30 Zn 31 Ga 33 As 34 Se 35 Br 36 Kr 55.85 72.61 38.21 40.08 44.96 47.88 50.94 52.00 55.85 58.93 58.69 63.55 65.39 69.72 74.92 78.96 79.90 83.80 2 + 3 d 5 1 + 4 s 0 2 + 4 s 0 3 + 3 d 0 4 + 3 d 0 3 + 3 d 2 3 + 3 d 3 3 + 3 d 5 2 + 3 d 7 2 + 3 d 8 2 + 3 d 9 2 + 3 d 10 3 + 3 d 10 96 312 1043 1390 629 37 Rb 38 Sr 39 Y 40 Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 49 In 50 Sn 51 Sb 52 Te 53 I 54 Xe 85.47 87.62 88.91 91.22 92.91 95.94 97.9 101.1 102.4 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 83.80 1 + 5 s 0 2 + 5 s 0 2 + 4 d 0 4 + 4 d 0 5 + 4 d 0 5 + 4 d 1 3 + 4 d 5 3 + 4 d 6 2 + 4 d 8 1 + 4 d 10 2 + 4 d 10 3 + 4 d 10 4 + 4 d 10 56 Ba 57 La 72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir 78 Pt 79 Au 80 Hg 81 Tl 82 Pb 83 Bi 84 Po 86 Rn 55 Cs 85 At 137.3 138.9 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 209 210 222 13.29 2 + 6 s 0 3 + 4 f 0 4 + 5 d 0 5 + 5 d 0 6 + 5 d 0 4 + 5 d 3 3 + 5 d 5 4 + 5 d 5 2 + 5 d 8 1 + 5 d 10 2 + 5 d 10 3 + 5 d 10 4 + 5 d 10 1 + 6 s 0 87 Fr 88 Ra 89 Ac 223 226.0 227.0 2 + 7 s 0 3 + 5 f 0 58 Ce 59 Pr 60 Nd 61 Pm 62 Sm 64 Gd 65 Tb 66 Dy 67 Ho 68 Er 69 Tm 70 Yb 71 Lu 63 Eu 140.1 140.9 144.2 145 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0 4 + 4 f 0 3 + 4 f 2 3 + 4 f 3 3 + 4 f 5 2 + 4 f 7 3 + 4 f 7 3 + 4 f 8 3 + 4 f 9 3 + 4 f 10 3 + 4 f 11 3 + 4 f 12 3 + 4 f 13 3 + 4 f 14 13 19 105 90 292 229 221 179 85 132 20 85 20 56 90 Th 91 Pa 92 U 93 Np 94 Pu 95 Am 96 Cm 97 Bk 98 Cf 99 Es 100 Fm 101 Md 102 No 103 Lr 259 232.0 231.0 238.0 238.0 244 243 247 247 251 252 257 258 260 4 + 5 f 0 5 + 5 f 0 4 + 5 f 2 5 + 5 f 2 Nonmetal Diamagnet Ferromagnet T C > 290K Paramagnet Antiferromagnet with T N > 290K Metal Antiferromagnet/Ferromagnet with T N /T C < 290 K Radioactive Magnetic atom BOLD Tokyo, 21xi 2011

Crustal abundances of magnetic elements T C ( ° C) J s (T) Fe 2.15 771 O Co 1.81 1087 Fe 5 Si Si Fe Ni 0.61 355 Log (abundance, ppm) 4 Al Al Al 3+ Mn Fe Fe 3 Mg Mg Cr Ni Ce O 2- Ca Ca 2 Nd Si 4+ Co Pr K Sm Gd Dy 1 Er Yb Na Na Eu Ho Tb H Tm Pm 0 Others Others -1 3 d elements 4 f elements Cr Mn Fe Co Ni Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Crustal abundances (top 9) All magnetic elements (log scale} Iron is 40 x as abundant as all the other magnetic elements taken together. Tokyo, 21xi 2011

Hysteresis Hysteresis M (Am -1 ) working M s point M r H coercivity H c H (Am - d 1 ) Any macroscopic magnet exhibiting remanence is in a thermodynamically- metastable state. Tokyo, 21xi 2011

The demagnetizing field The demagnetizing field B = μ 0 ( H + M ) Stray field B M H N S Demagnetizing field H d ≈ - N M ∇ B = 0 demagnetizing factor 0 ≤ N ≤ 1 Tokyo, 21xi 2011

Magnetic materials for applications Others Hard Magnets Hard Soft ferrite Hard ferrite Amorphous Magnets Fe, Sr, Ba, Nd, Sm, Ni-Fe/Fe-Co Co, Dy, Zr Nd-Fe-B Sm-Co Fe-Si (oriented) Alnico Others Soft Soft Magnets Co- γ Fe 2 O 3 (tapes, floppy discs) Magnets Fe, SI, Co, Ni, CrO2 (tapes) Iron (tapes) Zn, Mn Fe-Si Co-Cr (hard discs) Magnetic Magnetic Recording Recording Iron Fe, Ni, Co, Ta, Pt Ni-Fe/Fe-Co (heads) Others Breakdown of magnetic materials in 2000 - 30 B$ Tokyo, 21xi 2011

Summary of magnetic properties of useful materials λ T c M s (MAm -1 ) K (kJm -3 ) (10 -6 ) ( ° C) SmCo 5 847 0.86 17200 - Nd 2 Fe 14 B 315 1.28 4900 - CoPt 567 0.81 4800 - FePt 477 1.14 1800 - SrFe 12 O 19 467 0.38 330 - Fe 94 Si 6 770 1.68 48 -7 Co 35 Fe 65 940 1.95 20 -60 Ni 80 Fe 20 570 0.83 -1 2 (MnZn)Fe 2 O 4 300 0.50 -3 -5 (NiZn)Fe 2 O 4 590 0.33 -7 -25 Y 3 Fe 5 O 12 287 0.14 -2 -1 Tokyo, 21xi 2011

The permanent magnet market (~$10B) The permanent magnet market (~$10B) Sintered Ferrite Sintered Nd-Fe-B Nd,Dy,Tb,Fe,Co,B SrFe 12 O 1 Nd 2 Fe 14 9 B Bonded Ferrite Alnico; Fe,Co,Ni,Al Sm-Co; Sm, Co, Fe, Zr,Cu Bonded Nd-Fe-B Spindle motor Tonnage production: Voice-coil actuator Ferrite; 1,000,000 Nd-Fe-B; 80,000 Tokyo, 21xi 2011

The Limits The Limits Curie temperature T C . Should be > 550 K for RT applications Magnetization M s . Should be as large as possible. Many applications depend on M s 2 Energy product | BH | max Should be as large as possible for a permanent magnet | BH | max < ¼ μ 0 M s 2 Coercivity H c . Should be 0 for soft magnets, > ½ M s for hard magnets. Cost. As low as possible Tokyo, 21xi 2011

The Limits The Limits Curie temperature T C . Should be > 550 K for RT applications Magnetic ordering temperature of > 2000 materials Magnetization M s . Should be as large as possible. Many applications depend on M s 2 Energy product | BH | max Should Highest Néel Highest Curie temperature be as large as possible for a temperature permanent magnet | BH | max < α Fe 2 O 3 Fe Co ¼ μ 0 M s 2 Coercivity H c . Should be 0 for soft magnets, > ½ M s for hard Magnetic ordering magnets. temperature (K) Cost. As low as possible Tokyo, 21xi 2011

The Limits The Limits Slater-Pauling Curve Curie temperature T C . Should be Fe 65 Co 35 M s =1.95 MAm -1 > 550 K for RT applications m μ B Magnetization M s . Should be as Slope -1 large as possible. Many applications depend on M s 2 Energy product | BH | max Should be as large as possible for a permanent magnet | BH | max < ¼ μ 0 M s 2 Coercivity H c . Should be 0 for Cr Mn Fe Co Ni soft magnets, H c > ½ M s for hard Cu magnets. 6 7 8 9 10 11 Valence electrons Cost. As low as possible Tokyo, 21xi 2011

The Limits The Limits Curie temperature T C . Should be > 550 K for RT applications Energy product doubled ≈ Magnetization M s . Should be as every 12 years during the 20th century large as possible. Many applications depend on M s 2 Energy product | BH | max Should be as large as possible for a permanent magnet | BH | max < ¼ μ 0 M s 2 Coercivity H c . Should be 0 for soft magnets, > ½ M s for hard magnets. Cost. As low as possible Tokyo, 21xi 2011

The Limits The Limits Curie temperature T C . Should be > 550 K for RT applications Magnetization M s . Should be as large as possible. Many applications depend on M s 2 Energy product | BH | max Should be as large as possible for a permanent magnet | BH | max < ¼ μ 0 M s 2 Coercivity H c . Should be 0 for soft magnets, > ½ M s for hard magnets. The main achievement of technical magnetism in the 20th century was mastery Cost. As low as possible of coercivity 1900 : 10 3 < H c < 10 5 A m -1 1 < H c < 2 10 7 A m -1 2000 : Tokyo, 21xi 2011