Formulario de Login Angular2

formularioLogin.ts

########### Erro apresentado ###########

      { MongooseError: Path `login` is required.
          at ValidatorError (C:\GitHub\eSports-team\Back\node_modules\mongoose\lib\error\validator.js:24:11)
          at validate (C:\GitHub\eSports-team\Back\node_modules\mongoose\lib\schematype.js:705:13)
          at C:\GitHub\eSports-team\Back\node_modules\mongoose\lib\schematype.js:750:9
          at Array.forEach (native)
          at SchemaString.SchemaType.doValidate (C:\GitHub\eSports-team\Back\node_modules\mongoose\lib\schematype.js:711:19)
          at C:\GitHub\eSports-team\Back\node_modules\mongoose\lib\document.js:1408:9
          at _combinedTickCallback (internal/process/next_tick.js:73:7)
          at process._tickCallback (internal/process/next_tick.js:104:9)
        message: 'Path `login` is required.',
        name: 'ValidatorError',
        properties: [Object],
        kind: 'required',
        path: 'login',
        value: undefined,
        reason: undefined } },
  message: 'Usuario validation failed',
  name: 'ValidationError' }

########### Formulario HTML ###########

<form novalidate #meuForm="ngForm" (submit)="logar($event)">

      <div class="form-group row">
        <label for="login">Nome:</label>
        <input required name="login" #login="ngModel" [(ngModel)]="usuario.login" type="text" class="form-control" id="login" placeholder="Seu login...">
      </div>

      <div class="form-group row">
        <label for="senha">Senha:</label>
        <input required name="senha" #senha="ngModel" [(ngModel)]="usuario.senha" type="password" class="form-control" id="senha" placeholder="Sua senha...">
      </div>

      <div class="row">
        <div class="col">
          <button type="submit" class="btn btn-primary btn-lg">Entrar </button> 
        </div>
        <br>
        <div class="col">
          <p><a href="#">Esqueceu sua senha?</a></p>
        </div>
      </div>
    </form>

########### Login Componente ###########
           
  logar(){

      this.service.logar(this.usuario)
        .then( res => {
          console.log('Logando...')
        })
        .catch(erro => console.log(erro))
        
  }

########### Login Service ###########
        
        logar(usuario: UsuarioComponent): Promise<any> {
    return this.http.post(this.url, JSON.stringify(usuario))
      .toPromise()
        .then( res => {
          var token = res.headers.get('x-access-token');
                    if (token) {
                        this._loggedIn.next(true);
                        localStorage.setItem('token', token);
                    }
        })
        .catch( err => console.log(err))
  }